Virtue consists in a will which is in agreement with Nature. The wicked, though perforce they obey God’s law, do so involuntarily; in the simile of Cleanthes, they are like a dog tied to a cart, and compelled to go wherever it goes.
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

“In one sense, every life is in harmony with Nature, since it is such as Nature’s laws have caused it to be; but in another sense a human life is only in harmony with Nature when the individual will is directed to ends which are among those of Nature. Virtue consists in a will which is in agreement with Nature. The wicked, though perforce they obey God’s law, do so involuntarily; in the simile of Cleanthes, they are like a dog tied to a cart, and compelled to go wherever it goes. In the life of an individual man, virtue is the sole good; such things as health, happiness, possessions, are of no account. Since virtue resides in the will, everything really good or bad in a man’s life depends only upon himself.” source