The soul is what moves the body and perceives sensible objects
 Bertrand Russell, A History of Western Philosophy (1945). copy citation

Context

“All the other parts of soul, it is evident from what we have said, are, in spite of certain statements to the contrary, incapable of separate existence” (413b) . The mind is the part of us that understands mathematics and philosophy; its objects are timeless, and therefore it is regarded as itself timeless. The soul is what moves the body and perceives sensible objects; it is characterized by self-nutrition, sensation, thinking, and motivity (413b) ; but the mind has the higher function of thinking, which has no relation to the body or to the senses. Hence the mind can be immortal, though the rest of the soul cannot.” source