Suppose it were a matter of life and death to ten men to walk to York from London in a day.

Were this feat a possible one, they might no doubt each do their best to help the others to accomplish it.

But if it were beyond the power of each singly, they would not accomplish it as a body, by the whole ten leaving Charing Cross together, and each of them walking one tenth of the way.

The distance they could all walk would be no greater than the distance they could each walk.

In the same way the value of human life, as a whole, depends on the capacities of the individual human being, as an enjoying animal.