Simul flare sorbereque haud facile Est: ego hic esse et illic simul, haud potui. To blow and to swallow at the same time is not easy; I cannot at the same time be here and also there. PlautusMostellaria. Act III. 2. 105.
Certum est quia impossibile est. The fact is certain because it is impossible. TertullianDe Carne Christi. Ch. V. Pt. II. Called Tertullians rule of faith. Also given Credo quia impossibile. I believe because it is impossible. Same idea in St. AugustineConfessions. VI. 5. (7). Credo quia absurdum est. An anonymous rendering of the same.