The facts as to the position of an opponent accurately observed and correctly reported at a given moment, afford no reliable guarantee of his position 48 hours later, when the orders based on this information enter upon execution.
There, on the river Darejya, assuming that the passage (Vend., 19, 4) is correctly interpreted, stood the house of his father; and the Bundahish (20, 32 and 24, 15) says expressly that the river Daraja lay in Airan Vej, on its bank was the dwelling of his father, and that there Zoroaster was born.
Not even the coasts of western Africa are laid down correctly, although the author claimed to have taken part in one of the Portuguese expeditions.
There are some principles which, as soon as they are presented to the mind and correctly grasped, must be assented to; we see the truth!
He was the first correctly to solve Aristotle's problem, stated above, and to apply it practically to solar observations in a darkened room (Cosmographia, 1 535).