Ab absurdo - From the absurd (establishing the validity of your argument by pointing out the absurdity of your opponent's position)

Ab/Ex uno disce omnes - From one person, learn all people

Ad augusta per angusta - To high places by narrow roads

Ad hominem - Appealing to a person's physical and emotional urges, rather than her or his intellect

Aequam memento rebus in arduis servare mentem - Remember when life's path is steep to keep your mind even. (Horace)

Amare et sapere vix deo conceditur - Even a god finds it hard to love and be wise at the same time

Amicus certus in re incerta cernitur - A true friend is discerned during an uncertain matter

An nescis, mi fili, quantilla sapientia mundus regatur? - Don't you know then, my son, how little wisdom rules the world?

Anguis in herba - A snake in the grass. A treacherous person. (Vergil)

Aquila non captat muscas - The eagle doesn't capture flies (don't sweat the small things)

Arbiter elegantiae - Judge in matters of taste

Assiduus usus uni rei deditus et ingenium et artem saepe vincit - Constant practice devoted to one subject often outdues both intelligence and skill. (Cicero)

Astra non mentiuntur, sed astrologi bene mentiuntur de astris - The stars never lie, but the astrologs lie about the stars

Aude sapere - Dare to know

Aut viam inveniam aut faciam - I will either find a way or make one

Cogito Ergo Doleo

To err is human