Let not his confidence be without knowledge, nor his knowledge without steadfastness: let him always abide by what he has once determined, and let there be no erasure in his doctrines. It will be understood, even though I append it not, that such a man will be tranquil and composed in his demeanour, high-minded and courteous in his actions. Let reason be encouraged by the senses to seek for the truth, and draw its first principles from thence: indeed it has no other base of operations or place from which to start in pursuit of truth: it must fall back upon itself. Even the all-embracing universe and God who is its guide extends himself forth into outward things, and yet altogether returns from all sides back to himself. Let our mind do the same thing: when, following its bodily senses it has by means of them sent itself forth into the things of the outward world, let it remain still their master and its own. By this means we shall obtain a strength and an ability which are united and allied together, and shall derive from it that reason which never halts between two opinions, nor is dull in forming its perceptions, beliefs, or convictions.