时间与自由意志 (导读注释版)(世界学术经典系列)

It is not enough to say that number is a collection of units;we must add that these units are identical with one another,or at least that they are assumed to be identical when they are counted.No doubt we can count the sheep in a flock and say that there are fifty,although they are all different from one another and are easily recognized by the shepherd:but the reason is that we agree in that case to neglect their individual differences and to take into account only what they have in common. On the other hand,as soon as we fix our attention on the particular features of objects or individuals,we can of course make an enumeration of them,but not a total.We place ourselves at these two very different points of view when we count the soldiers in a battalion and when we call the roll.Hence we may conclude that the idea of number implies the simple intuition of a multiplicity of parts or units, which are absolutely alike.