Justin Taylor quotes C.S. Lewis on the three components of human morality. Here’s just a taste:
He asks us to think of humanity as “a fleet of ships sailing in formation” and what makes it successful:
The voyage will be a success only, in the first place, if the ships do not collide and get in one another’s way; and, secondly, if each ship is seaworthy and has her engines in good order.
As a matter of fact, you cannot have either of these two things without the other.
If the ships keep on having collisions, they will not remain seaworthy very long.
On the other hand, if their steering gears are out of order, they will not be able to avoid collisions.