Nature is full of by-ends. A moth feeds on a petal, in a moment the pollen caught on its breast will be wedding this blossom to another in the next county.
Error held as truth has much the effect of truth. In politics and religion this fact upsets many confident predictions.
Dumbness and silence are two different things.
Let truth be a banner big enough to hide the man who holds it up.
Is any knowledge worthless? Try to think of an example.
A man's own addition to what he learns is cement to bind an otherwise loose heap of stones into a structure of unity, strength, and use.