these words "know" and "understand," while all the time we are ignorant of what "knowledge" is. We must try again to define the term; and first, to have is quite different from to possess knowledge. Our soul is like an aviary full of wild birds, flying all about the place, singly or in groups. You may possess them, but you have none in hand; and until you collect, comprehend, and grasp your winged thoughts, you cannot be said to have them either. When you have once caught your bird (or your thought), you cannot mistake it; but while they are flying about, you may mistake the ring-dove for the pigeon, and so you may mistake the various numbers and forms of knowledge.
"Perhaps," says Theatetus, sharply, there may be sham birds in the aviary; and you may put forth your hand intending to grasp Knowledge, but catch Ignorance instead. How then?"
"No," says Socrates; "it is a clever suggestion, but if you once know the form of knowledge, you will never mistake it for ignorance. Perhaps, however, there may be higher forms of knowledge in other aviaries, which help you to tell the wrong from the right thought; but on this supposition we might go on imagining forms to infinity."
A third and last definition of knowledge is now proposed—"True opinion plus definition or explanation." But what is explanation?—is it the expression of a man's thoughts? But every one who is not deaf and dumb can express his thoughts. Or is it the enumeration of the elements of which anything is composed? But you may know the syllables of a name without
