A man does not need to have seen or experienced everything himself. But if he is to commit himself to another's experiences and his way of putting them, let him consider that he has to do with three things—the object in question and two subjects.
The supreme achievement would be to see that stating a fact is starting a theory.
If I acquiesce at last in some ultimate fact of nature, it is, no doubt, only resignation; but it makes a great difference whether the resignation takes place at the limits of human faculty, or within the hypothetical boundaries of my own narrow individuality.
If we look at the problems raised by Aristotle, we are astonished at his gift of observation. What wonderful eyes the Greeks had for many things! Only they committed the mistake of being over-hasty, of passing straightway from the phenomenon to the explanation of it, and thereby produced certain theories that are quite inadequate. But this is the mistake of all times, and still made in our own day.
Hypotheses are cradle-songs by which the teacher lulls his scholars to sleep. The thoughtful and honest observer is always learning more and more of his limitations; he sees that the further knowledge spreads, the more numerous are the problems that make their appearance.