How much does a person miss a small amputated part like a little toe compared to losing a whole hand?
A person who loses a little toe misses it almost as much as a whole hand, according to the illustration. The reason is that even the smallest, most feeble member of the body is not to be dismissed; every part matters and its loss is keenly felt.
Les teaches from the passage that the eye cannot say to the hand, "I have no need of thee," nor can the head say to the feet, "I have no need of you." He then gives the illustration that if you ask someone who had one amputated, they will miss that little toe almost as much as they would a complete hand. The point is that even the most feeble member is not unimportant; the body's parts are mutually dependent, and the loss of even a small part is felt.
And the eye cannot say unto the hand, I have no need of thee: nor again the head to the feet, I have no need of you.