What does posse ad esse non valet consequentia mean?
a posse ad esse non valet consequentia = "the consequence does not follow from the possible to the real."
What does ab esse ad posse valet illatio mean?
Hence that proverb, so well known in the Schools, derives its force; 'ab esse ad posse valet illatio,' which may be freely translated, 'If a thing is or ever was, it is fair to infer that it can be. ' But the same concept of possible Being may be acquired also a priori.