strong active powers need a strong intellect; strong intellect needs strong sympathies, to keep life steady.
 William James, The Varieties of Religious Experience (1902). copy citation

Context

“Excess, in human faculties, means usually one-sidedness or want of balance; for it is hard to imagine an essential faculty too strong, if only other faculties equally strong be there to coöperate with it in action. Strong affections need a strong will; strong active powers need a strong intellect; strong intellect needs strong sympathies, to keep life steady. If the balance exist, no one faculty can possibly be too strong—we only get the stronger all-round character. In the life of saints, technically so called, the spiritual faculties are strong, but what gives the impression of extravagance proves usually on examination to be a relative deficiency of intellect.” source