Quote Originally Posted by Lampada View Post
"You can lead a human to knowledge but you cannot make him think."
Or, as Dorothy Parker punningly said: "You can lead a horticulture [whore to culture], but you cannot make her think."

And, on the problem of promoting "safe sex" practices in the age of HIV, one might also say:

"You can lead a horse to Trojans, but you cannot make him wear one."