philosophy: to give inward light, to teach true self-measurement. In one passage, much misunderstood, Plato has called this philosophic art the due measurement of pleasures and pains. It should scarcely have been possible to mistake the meaning. But, with the catchwords of Utilitarianism ringing in their ears, the commentators ran straight contrary to the true teaching of the _Protagoras_, consentient as it is with that of the _Phaedo_ and the _Philebus_. To measure, one must have a standard: and if Plato has one lesson always for us, it is that a sure standard the multitude have not, but only confusion. The so-called pleasures and pains of the world’s experiences are so entitled for different reasons, for contrary aims, and with no unity or harmony of judgment. They are—not a fact to be accepted, but—a problem for investigation: their reality is in question, their genuineness, solidity and purity: and till you have settled that, you cannot measure, for you may be measuring vacuity under the idea that there is substance. You have still to get at the unit—i.e. the reality of pleasure. It was not Plato’s view that pleasure was a separate and independent entity: that it was exactly as it was felt. Each pleasure is dependent for its pleasurable quality on the consciousness it belongs to, and has only a relative truth and reality. Bentham has written about computing the value of a “lot” of pleasures and pains. But Plato had his mind on an earlier and more fundamental problem, what is the truth and reality of pleasure; and his fullest but not his only essay towards determining the value or estimating the meaning of pleasure in the scale of being is that given in the _Philebus_.