If we will disbelieve everything, because we cannot certainly know all things, we shall do much what as wisely as he who would not use his legs, but sit still and perish, because he had no wings to fly.
6.

Knowledge of our Capacity a Cure of Scepticism and Idleness.
When we know our own strength, we shall the better know what to undertake with hopes of success; and when we have well surveyed the POWERS of our own minds, and made some estimate what we may expect from them, we shall not be inclined either to sit still, and not set our thoughts on work at all, in despair of knowing anything; nor on the other side, question everything, and disclaim all knowledge, because some things are not to be understood.

It is of great use to the sailor to know the length of his line, though he cannot with it fathom all the depths of the ocean.

It is well he knows that it is long enough to reach the bottom, at such places as are necessary to direct his voyage, and caution him against running upon shoals that may ruin him.

Our business here is not to know all things, but those which concern our conduct.