The working, active, and acting nature of anything, is the life of it; and that which makes us call a thing alive, is, that we observe an active nature in it.
This active, working nature in man is the spirit which he has within him. And as his body without this spirit is, dead, so faith without works is dead also.
And if we would know what the working active thing in true faith is, the apostle tells us in Gal. v. 6, "Faith worketh by love." So that it is love which is the active working spirit in all true faith. This is its very soul, without which it is dead.
Taken from the book Charity and its Fruits by Jonathan Edwards 1668–1759