judge, according to merely mechanical laws, of the possibility of all events in material nature, and consequently of all forms regarded as its products, I do not therefore say: They are possible in this way alone (apart from any other kind of causality).

All that is implied is: I must always reflect upon them according to the principle of the mere mechanism of nature, and consequently investigate this as far as I can; because unless this lies at the basis of investigation, there can be no proper knowledge of nature at all. But this does not prevent us, if occasion offers, from following out the second maxim in the case of certain natural forms (and even by occasion of these in the whole of nature), in order to reflect upon them according to the principle of final causes,