Happiness lies in virtuous activity, and perfect happiness lies in the best activity, which is contemplative.
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

“There are things that are valued more than pleasure; no one would be content to go through life with a child’s intellect, even if it were pleasant to do so. Each animal has its proper pleasure, and the proper pleasure of man is connected with reason.
This leads on to the only doctrine in the book which is not mere common sense. Happiness lies in virtuous activity, and perfect happiness lies in the best activity, which is contemplative. Contemplation is preferable to war or politics or any other practical career, because it allows leisure, and leisure is essential to happiness. Practical virtue brings only a secondary kind of happiness; the supreme happiness is in the exercise of reason, for reason, more than anything else, is man.” source