Bertrand Russell Quotes（バートランド・ラッセルの名言・警句)

　

Great difficulties are associated with the null-class, and generally with the idea of nothing. It is plain that there is such a concept as nothing, and that in some sense nothing is something. In fact, the proposition nothing is not nothing is undoubtedly capable of an interpretation which makes it true--a point which gives rise to the contradictions discussed in Plato's Sophist.
The Principles of Mathematics, 1903, Chap. VI. Classes: §73　Source:
　More info.:http://fair-use.org/bertrand-russell/the-principles-of-mathematics/s73