Common sense is accustomed to the division of the world into mind and matter.
 Bertrand Russell, Mysticism and Logic and Other Essays (1910). copy citation

Context

“My main position, which is realistic, is, I hope and believe, not remote from that of Professor Alexander, by whose writings on this subject I have profited greatly. [24] It is also in close accord with that of Dr. Nunn. [25] Common sense is accustomed to the division of the world into mind and matter. It is supposed by all who have never studied philosophy that the distinction between mind and matter is perfectly clear and easy, that the two do not at any point overlap, and that only a fool or a philosopher could be in doubt as to whether any given entity is mental or material.” source