Page:Our knowledge of the external world.djvu/181

 property of being unable to be counted is characteristic of infinite collections, and is a source of many of their paradoxical qualities. So paradoxical are these qualities that until our own day they were thought to constitute logical contradictions. A long line of philosophers, from Zeno to M. Bergson, have based much of their metaphysics upon the supposed impossibility of infinite collections. Broadly speaking, the difficulties were stated by Zeno, and nothing material was added until we reach Bolzano’s Paradoxien des Unendlichen, a little work written in 1847-8, and published posthumously in 1851. Intervening attempts to deal with the problem are futile and negligible. The definitive solution of the difficulties is due, not to Bolzano, but to Georg Cantor, whose work on this subject first appeared in 1882.

In order to understand Zeno, and to realise how little modern orthodox metaphysics has added to the achievements of the Greeks, we must consider for a moment his master Parmenides, in whose interest the paradoxes were invented. Parmenides expounded his views in a poem divided into two parts, called “the way of truth” and “the way of opinion”—like Mr Bradley’s “Appearance” and “Reality,” except that Parmenides tells us first about reality and then about appearance. “The way of opinion,” in his philosophy, is, broadly speaking, Pythagoreanism; it begins with a warning: “Here I shall close my trustworthy speech and thought about the truth. Henceforward learn the opinions of mortals, giving ear to the deceptive ordering of my words.” What has gone before has been revealed by a goddess, who tells him what