The truth is, look upon the law in its purity, holiness, compass, and perfection; its manner of delivery, with dread, terror, thunder, earthquakes, fire; the sanction of it, in death, curse, wrath; and it makes a wonderful discovery of sin, upon every account: its pollution, guilt, and exceeding sinfulness are seen by it. But yet all this doth not suffice to give a man a true and thorough conviction of sin. Not but that the glass is clear, but of ourselves we have not eyes to look into it; the rule is straight, but we cannot apply it: and therefore Christ sends his Spirit to convince the world of sin, John 16:8; who, though, as to some ends and purposes, he makes use of the law, yet the work of conviction, which alone is a useful knowledge of sin, is his peculiar work. And so the discovery of sin may also be said to be by Christ,—to be part of the wisdom that is hid in him.
– John Owen –
from Of Communion With God, volume 2 of Works, page 95