[RobbyS]

Aquinas did not have a microscope at his disposal.

[Mike Fieschko]

Aquinas did not have a microscope at his disposal.

Quite true. Yet the division between 'form' and 'matter' which he developed from Aristotle might have restricted his ability to identify the time when 'humanness' reaches existence. Did Aquinas ever discuss tadpoles? (Not meant in jest.)