I once heard about how animal catchers used to catch wild monkeys for zoos. I was told that they would set an empty glass pop bottle in an open field with a peanut dropped into it. Then they'd hide in the bushes and wait. After a while, a monkey would sneak up to the pop bottle, squeeze its paw down into the narrow neck of the bottle and grab the peanut. Once it had grabbed ahold of the peanut, it couldn't withdraw its peanut-filled paw from the pop bottle. Then, all that the catchers had to do was walk out and take the monkey into captivity - pop bottle and all. They could walk, not run; because no matter what might be about to happen to him, the greedy little monkey would refuse to let go of the peanut.
Would-be followers of Jesus are often like that monkey. They hear about Jesus, and they even begin to follow; but they also won't let go of the grip they have on the possessions of this life - the income, the home, the cars, the life-style, the security. They would like to follow Jesus dragging their 'pop-bottle' of this world's riches in tow if Jesus would accept that. But when Jesus suddenly turns to them and says, "Whoever of you does not forsake all that he has cannot be My disciple;" they find that the cost is higher than they are willing to pay; and they can't go any further.