We have suggested that happiness comes with fulfillment and that fulfillment requires virtue. Virtue enables us to acquire the goods we need to become all that we might.

We have also claimed that virtue may be described as emotion moderated by reason. The virtue of temperance allows us to moderate pleasure so that we act with the future in mind and thereby focus on real rather than apparent goods. Courage enables us to endure pain and discomfort in the present so that we may have a better future. Pain and pleasure are emotions. And so are fear, sadness, envy, jealousy, anger, and so many more. But according to Aristotle, emotion is much more than feeling. Emotion involves thoughts, desire, and actions as well as feelings. We fear something because we think it may harm us. If something is harmful we of course want to avoid it. Finally, we act; we run away from that which we think can harm us. To take another example, we are sad because we know that we have suffered a loss. We desire the thing that we have lost and wish its return. And we weep over our loss, as we act upon our feeling.

Having reviewed Aristotle's thoughts on the development of virtue we will now take a look at some contemporary psychological thinking on the subject. When psychology became an empirical science in the late nineteenth century, concepts like virtue and character went largely unnoticed because they could not be examined in the laboratory. Even today the suspicion of philosophical concepts endures in psychology. However, things are changing. Peterson and Seligman have produced a scholarly and impressively comprehensive handbook on the subjects of character and virtue. Rather than avoiding the philosophical literature they have embraced portions of it to set the stage for a psychological analysis of what they deem the major virtues and noting that they are desperately needed to redirect our society. “After a detour through the hedonism of the 1960s, the narcissism of the 1970s, the materialism of the 1980s, and the apathy of the 1990s, most everyone today seems to believe that character is important after all.” Peterson and Seligman do a wonderful job of describing certain core virtues that seem to transcend culture. The theory and evidence they review includes what psychologists have for many years referred to as moral development. The psychological study of moral development addresses many of the issues raised by Aristotle, including the limited cognitive abilities of young children and the need for careful guidance during this period.

Nathaniel Hawthorne claimed that happiness comes to us like a butterfly, alighting on our shoulder when we least expect it. That's a wonderfully romantic idea but probably wrong. A good life usually comes slowly, over time, and requires effort. Benjamin Franklin said “The Declaration only guarantees the American people the right to pursue happiness. You have to catch it yourself.”

Happiness requires the satisfaction of many needs. Remember Maslow's hierarchy and that, depending upon our place along the hierarchy, we desire and seek the things that we need. For the hungry it is nourishment, for the homeless it is security, and for the lonely it is friendship.

According to Aristotle, the things we seek are “goods.” Goods may differ among us – what is a good for one person may be of little interest to another if they are at different places along the hierarchy of needs. Poetry, science, and philosophy are of little importance to the hungry and the fearful. Goods are defined relative to needs and needs lower on the hierarchy must come first.

Aristotle was a teleologist; he believed that we are goal seeking and that all behaviors have an aim, an end, or a purpose.

The final chapters of Aristotle's Nichomachaen Ethics take a surprising turn. Throughout the Ethics we learn that a good human life requires intellectual and moral virtue. The key to happiness is found in virtue because courage, temperance, justice, friendship, and the like, allow us to acquire the real goods we need to fulfill potentials. A life of pleasure may be enjoyable in the short term but practical wisdom and the golden mean win out in the end. Virtue is good for the individual and good for the polis.

At the end of the Ethics, Aristotle seems to tell a different story: True happiness, he claims, is found in contemplation. Reason is the foundation of virtue, which enables us to navigate the everyday world. But reason can also lead us to another realm. It is possible to transcend the world of needs, material goods, and practical problems and enter the world of forms – the world of knowledge, truth, perfection, and God. Contemplation is the means by which we can travel to the “ultimate concerns.” Now, Aristotle returns us to his mentor, to Plato.

The origins of mechanics – both the practical development of devices and the creation of a body of theory about their operation – are obscure. Doubtless elements of the discipline, such as the use of lever and balance, axle-and-wheel, clepsydra and siphon, predated the fourth century bce. However, the creation of a discipline requires more than the use of certain kinds of technology: there needs to be some kind of unifying idea, some perception of commonality. Looking at the disparate elements that came to be included in the Greek discipline of mechanics, it is difficult to identify exactly what that perceived commonality was. It may be that the reason why mechanics came to be recognized as a discipline – a field of knowledge – was no more than a recognition that certain devices make possible results that would not have occurred without them, and that some of them worked in similar ways. The contribution of mechanics to the history of philosophy arose from its ensuing theories, as well as a more general commitment to the idea that the principles at work in mechanics can also be found in the natural world.

This chapter will examine the evidence concerning the creation of a discipline called ‘mechanics’ during the fourth century. Such a reconstructive project requires great caution against reading back assumptions about what ‘mechanics’ means, or about what is self-evident. In the end, I find the evidence from the fourth century to be inconclusive.

Texts have survived from the Hellenistic period concerning a so-called pneumatikē technē. I shall refer to the field as ‘pneumatics’, although – as scholars have noted – the English transliteration does not exactly capture the sense of the subject matter, which concerns devices worked by flowing water, compressed air or steam. As Landels aptly suggests, the German title Druckwerke best captures the sense: although there are some anomalies, the field is largely about what might be called pressure effects.

The characterization of pneumatics as delimited by pressure-driven devices is, admittedly, a simplification of a vaguely defined field, and it works better for Hero's collection than for Philo's. The latter – especially in the more extensive Arabic version – includes a number of water wheels, which do not depend on pressure differentials so much as the simple weight of water. Both Pappus and Philoponus describe a branch of mechanics as being concerned with devices that raise water, perhaps by analogy parallel to the category of devices used to lift weights. However, the vast majority of devices in the pneumatica collections use pressure differentials to regulate the flow of water in different ways.

I have previously discussed the classical philosophical theories offered to account for ‘rarefaction effects’. Some pneumatic devices of the Hellenistic era work by the reverse procedure, forcing air into a smaller place than it otherwise occupies. These ‘compression effects’, as I call them, are credited to Ctesibius.

In outlining the history of the discipline, I have already indicated a number of ways in which specific theories and concepts provoked philosophical responses from the mechanical theorists themselves. I shall now consider evidence from ancient Greek natural philosophers – including philosophically inclined medical theorists – concerning the reception of ideas from mechanics.

On a number of specific issues, natural philosophers engaged with the implications of mechanical theory and took seriously the question of its relationship to natural philosophy. There is, moreover, some evidence of a commitment, in a few ancient thinkers, to the use of mechanics as a heuristic. There are reports in late antiquity of those who considered whether the natural world might be understood to ‘work like that’: to function in ways that could be illuminated by appeal to the working artifacts that were available at the time. This latter evidence tends to cluster in three areas: the functioning of organisms, the motion of the heavenly bodies, and – at a more general level – the operation of causality in nature as a whole in relation to a directing intelligence.

The existence of complex working artifacts exhibiting regular, pre-programmed causal sequences in their operation showed vividly what could be achieved by material arrangement alone. This, in turn, threatened some of the classic arguments for teleological explanations, which are typically based on the impossibility of adequate explanation of the phenomena using the resources of materialism alone.

It is a commonplace that the Hellenistic period was a time of great productivity in the sciences. The patronage of the court of the Ptolemies made Alexandria in particular a centre for work in many fields, including medicine, mathematics, mechanics and astronomy. Many scientific and philosophical texts from the period are lost or survive only in part; the dates of many key figures are unknown. Nonetheless, there is evidence of much work in mechanics – theory and practice – in the post-Aristotelian period. Some texts have survived that attempt to unify, analyse and explain the techniques of mechanics. There are reports of devices involving valves, pistons and pumps, water-lifting screws, water organs, catapults, steam devices, pneumatic toys and display pieces, theatrical automata and planetary models. Archaeological finds have also yielded some physical evidence of the technology available and indicate that the sophistication of the technology exceeds that described in the surviving literary evidence. Despite much uncertainty and questionable evidence, it is clear that engineering advanced considerably, particularly during the Hellenistic period; there were also attempts to develop theories to explain the operation of mechanical devices.

There is some uncertainty about the extent to which scientific ideas filtered through to the Athenian philosophical schools during the Hellenistic period. Athens continued to be the philosophical centre for more than two centuries following Aristotle's death, spatially separated from the major hub of the natural sciences in Egypt. Philosophers during this period seem to have increasingly turned away from natural philosophy to other topics.

In this chapter I consider issues that form an essential background to the question how the development of ancient mechanics might have impacted on ancient natural philosophy. Such an impact could take different forms, and it is important to be clear on what would count as a ‘mechanical’ or ‘mechanistic’ conception, using the term to describe a way of conceiving of the natural world by reference to mechanics. The question needs to be posed in a way that is neither too broad nor too narrow in scope, in order to appreciate what effects the discipline of mechanics might have had on natural philosophy.

At a time when mechanics was understood to work because of principles that could be identified and theorized, we might expect philosophers to consider the applicability of these principles to the study of other kinds of motion and its causes. But it is also possible for natural philosophers to take inspiration from mechanics independently of such a theoretical understanding. Experience with constructing devices might give rise to new ideas about the properties of matter, or the way it interacts. The presence of working artifacts that can approximate the functions taken to be definitive of animals might call into question the distinction in kind between organism and artifact, or suggest ways that animal functions might be realized by material means.

Historians agree on the importance, both to natural philosophy and to the development of the modern sciences, of the emergence of a ‘mechanical world picture’: many have studied its history, defining features and governing motivations. One important reason for the development of this world picture in the early modern period seems to have been the reintroduction of a number of ancient Greek texts. Rose and Drake suggest that it is no coincidence that the circulation of the Aristotelian Mechanica coincided with the formative period for modern science.

Against this background, it might seem necessary to account for the absence of any comparable interest, amongst the ancient Greeks themselves, in the implications of their mechanics for natural philosophy. A number of classic explanations have been offered as to why ancient Greek thinkers might not have seen the applicability of ideas from mechanics to the understanding of the natural world. I suggest that these explanations are spurious, and moreover that there is evidence of a philosophical reception of ideas from mechanics, especially in late antiquity. The evidence is scattered and often only preserved in the criticisms of its detractors: the dominant figures in late antique philosophy rejected the ‘mechanical hypothesis’. But its very existence is an interesting development that should not be overlooked.

Ancient Greek mechanics was a broad and diverse field, including a number of subfields concerned with different kinds of ‘working artifacts’ and the theory of their operation.

It is only in the seventeenth century that the term ‘mechanical’ came into common use to describe a way of doing natural philosophy. This appendix draws on the results of recent scholarly work on this period in disentangling different threads in the complex history of the term ‘mechanical’. There are several reasons for attempting to trace the reception of the ancient Greek tradition of mechanics in the seventeenth century. One is to show why twentieth-century usage, based as it is on an opposition that was formulated in the early modern period, is so multifaceted. A second is to justify my rejection of a scholarly commonplace that a view of mechanics Galileo rejects goes back to antiquity. The third is to indicate that the sense in which I have been writing of a ‘mechanical hypothesis’ in late antiquity is similar to the sense in which that phrase came to be used in the seventeenth century. Comparisons between the ancient and modern reception of mechanics are most often made by experts in the latter period; I hope it does not seem unduly hubristic to trace that reception from a different perspective. This is not of course intended as a complete account of the meanings of ‘mechanical’ in the seventeenth century but rather focuses on the reception of ‘mechanics’ in the ancient Greek sense. Because modern categories are shaped by seventeenth-century usage, attention to the shaping of those categories is a task that scholars of ancient Greek thought cannot avoid.