In Lesbos he did original work in marine biology. "We must not feel a childish disgust at the investigation of the meaner animals. For there is something marvellous in all natural things.In his detailed studies, Aristotle refers to over 500 different species. He insisted on the study of particulars - 'what is better known to us' - before theorising. He took on the enormous task of the classification of life forms. His work here mirrors his more general attempt at the classification of knowledge.