Love shows a human being the purpose of his life; reason shows him the means of fulfilling it.
The sun shines its light unceasingly on the whole world, but doing this does not exhaust its light; your reason must shine just like this, radiating in all directions. It flows everywhere, without becoming exhausted, and, when it encounters an obstacle, it must show neither irritation nor anger, but must calmly illuminate everything that thirsts to accept it, without sinking, without becoming tired, covering everything that faces the light and leaving in the shadow only that which itself turns away from it.
— Marcus Aurelius
Compared to the world around him, the human being is no more than a frail reed; but this reed has the gift of reason.
It takes very little to kill a human being. And yet, the human being is higher than all the beasts, higher than all earthly things, because even as he is dying, his mind is aware that he is dying. The human being can become aware of just how pitiful his body is before nature. Nature, however, is not conscious of anything.
Our advantage consists wholly in our ability to reason. Reason alone elevates us above the rest of the world. Let us appreciate and support our reason, and it will illuminate for us the whole of our life, it will show us what is good and what is evil.
— Pascal
Reason is the only thing that distinguishes a human being from an animal. Some develop it, but many neglect it; it is as if they want to renounce the only thing that separates them from cattle.
— Eastern wisdom
I glory in Christianity because it enlarges, invigorates, exalts my rational nature. If I could not be a Christian without ceasing to be rational, I should not hesitate as to my choice. I feel myself bound to sacrifice to Christianity property, reputation, life; but I ought not to sacrifice to any religion, that reason which lifts me above the brute and constitutes me a man. I can conceive no sacrilege greater than to prostrate or renounce the highest faculty which we have derived from God. In so doing we should offer violence to the divinity within us. Reason is the most glorious form or exercise of the intellectual nature. It corresponds to the unity of God and the universe, and seeks to make the soul the image and mirror of this sublime unity.
— Channing
If the human being did not have reason, he would be incapable of differentiating between good and evil, incapable of seeking and attaining the true good.