From Wiki, on Penn:

Penn's motto is based on a line from Horace’s Third Ode, quid leges sine moribus vanae proficiunt? ("of what avail empty laws without [good] mores?") From 1756 to 1898, the motto read Sine Moribus Vanae. When a wag pointed out that the motto could be translated as "Loose women without morals," the university quickly changed the motto to literae sine moribus vanae ("Letters without morals are useless"). In 1932, all elements of the seal were revised, and as part of the redesign it was decided that the new motto "mutilated" Horace, and it was changed to its present wording, Leges Sine Moribus Vanae ("Laws without morals [are] useless")