quod me nutrit me destruit. What nurishes me also destroys me.
qui audet adipiscitur S/he who dares wins (or: s/he who wins dares)
quem di diligunt, adolescens moritur Whom the gods love die young (only the good die young)
qui scribit bis legit He who writes reads twice
qui non est hodie cras minus aptus erit He who is not prepared today will be less so tomorrow.
qui tacet consentire Who is silent gives consent.
quid ni?
why not?
quid novi? What's new?
quis custodiet ipsos custodes? Who will watch the watchers themselves?
quod erat demonstrandum Which was to be proved
quod erat faciendum Which was to be done
quot homines tot sententiac So many men so many options
quod est inferius est sicut quod est superius, et quod est superius est
sicut quod est inferius ( Tabula Smaragdina or The Table of Emerald by Hermes Trismegistus).
As above so below