I have often wondered that, in so inquisitive an age as this, among those many learned men that have with much freedom, as well as acuteness, written of the works of nature (as they call them) – and some of them of the principles too – I have not met with any that has made it his business to write of nature herself. This will perhaps hereafter be thought such an omission as if, in giving an account of the political estate of a kingdom, one should treat largely of the civil judges, military officers and other subordinate magistrates, and of the particular ranks and orders of inferior subjects and plebeians, but should be silent of the prerogatives and ways of administration of the king; or (to use a comparison more suitable to the subject) as if one should particularly treat of the barrel, wheels, string, balance, index and other parts of a watch, without examining the nature of the spring that sets all these a moving. When I say this, I do not forget that the word ‘nature’ is everywhere to be met with in the writings of physiologers. But though they frequently employ the word, they seem not to have much considered what notion ought to be framed of the thing, which they suppose and admire, and upon occasion celebrate, but do not call in question or discuss.