Today Eratosthenes' method [of calculating the circumference of the earth] seems almost banal … yet it is inaccessible to prescientific civilizations… - Lucio Russo

Unfortunately, the optimistic view that "classical civilization" handed down certain fundamental works that managed to include the knowledge contained in the lost writings has proved groundless. In fact, in the face of a general regression in the level of civilization, it's never the best works that will be saved through an automatic process of natural selection.

Euclid … manages to obtain a rigorous proof without ever dealing with infinity, by reducing the problem [of the infinitude of primes] to the study of finite numbers. This is exactly what contemporary mathematical analysis does.

Since UFO stands for "unidentified flying object", the word ufology means approximately "knowledge about unknown flying objects", and is therefore a "science" whose content is void by definition. Similar considerations hold for parapsychology.