One of the difficulties with which scientific endeavour is fraught is that of maintaining detachment. The scientist's interest in his work will lead him to formulate hypotheses and the hypotheses will lead him to expectations about future observations. Is disinterested investigation then possible? Surely the very formulation of a hypothesis engenders a paternal affection and a desire to preserve it. Knowing this, however, the scientist is able to guard against his expectations influencing his observations, defending thus both his objectivity and his honour. But in cases where discriminations are exceptionally difficult to make, then here perhaps, in spite of fore-knowledge of the danger, and in spite of all precautions, an expectation may influence a judgement.

The most perplexing aspect of Galileo's work in physics is without doubt the sharp distinction one can draw between his essentially dynamic studies in such juvenilia as De Motu and the consciously kinematical approach of his later output—particularly the Two New Sciences. Whether one chooses to call this a shift from the “why” of motion to the “how”, or, as I should prefer, a shift from dynamics to kinematics, there can be no denying its existence. The Galileo who wrote that “The present does not seem to be the proper time to investigate the cause of the acceleration of natural motion …” is, on the face of it, a very different man from the one who had earlier written almost an entire treatise on precisely this topic.

Almost traditionally, it seems, accounts of the development of the concepts of work and energy have tended to describe them within the classical framework of Newtonian mechanics. They are seen as the end products of the celebrated vis-viva dispute in the eighteenth century: the outcome of a debate within the confines of the science of rational mechanics. I would like to suggest that this may be to take too narrow a view of the case. It is to project backwards our present specialist arrangement of scientific knowledge, our present divisions between the sciences, and to assume that past development was strictly guided by these divisions. And this is to make questionable historical and sociological assumptions.

From the very day in 1686 when Edmond Halley placed Book I of the Principia before the Royal Society, Robert Hooke's claim to prior discovery has been associated with the law of universal gravitation. If the seventeenth century rejected Hooke's claim summarily, historians of science have not forgotten it, and a steady stream of articles continues the discussion. In our own day particularly, when some of the glitter has worn off, not from the scientific achievement, but from the character of Newton, there has been a tendency vicariously to atone for the treatment Hooke received. The judgement Lohne cites with approval from Vavilov appears to summarize the current estimate of the issue—in the seventeenth century only Newton could have written the Principia; nevertheless Hooke first sketched out its programme. What with all the knocks he has received both alive and dead, one feels guilty (and perhaps superfluous) in assuming the role of “debunker” at this late date. Apologetically draped in sackcloth then, head covered with ashes (and with whatever it is one dons for superfluity) I venture softly to suggest that Hooke has received more than his due. There is no question here of justifying Newton's behaviour toward Hooke. Wholly lacking in generosity as it appears to me, Newton's behaviour neither deserves nor can receive justification. The question turns rather on Hooke's scientific theories. Granting always his lack of demonstrations, historians have been prone to interpret his words in the light of Newton's demonstrations. A close examination of Hooke's writings does not sustain the interpretation. Contrary to what is generally asserted, he did not hold a conception of universal gravitation. And if he announced the inverse square relation, he derived it from such a medley of confusion as will not allow his claim to priority.