Full Idea
Change occurs from possession to privation, but from privation to possession is impossible; one who has gone blind does not recover sight nor does a bald man regain his hair nor does a toothless man grow new ones.
Gist of Idea
Change goes from possession to loss (as in baldness), but not the other way round
Source
Aristotle (Categories [c.331 BCE], 13a35)
Book Reference
Aristotle: 'Categories and De Interpretatione', ed/tr. Ackrill,J.R. [OUP 1963], p.36
A Reaction
Although this seems like an insight into entropy, it isn't an accurate observation, since trees lose their leaves, and then regain them in spring. Maybe somewhere men regrow their hair each spring.