There is nothing like this progress of opposites in Plato, who in the Symposium denies the possibility of reconciliation until the opposition has passed away. In his own words, there is an absurdity in supposing that 'harmony is discord; for in reality harmony consists of notes of a higher and lower pitch which disagreed once, but are now reconciled by the art of music' (Symp.). He does indeed describe objects of sense as regarded by us sometimes from one point of view and sometimes from another. As he says at the end of the Fifth Book of the Republic, 'There is nothing light which is not heavy, or great which is not small.' And he extends this relativity to the conceptions of just and good, as well as to great and small. In like manner he acknowledges that the same number may be more or less in relation to other numbers without any increase or diminution (Theat.). But the perplexity only arises out of the confusion of the human faculties; the art of measuring shows us what is truly great and truly small. Though the just and good in particular instances may vary, the IDEA of good is eternal and unchangeable. And the IDEA of good is the source of knowledge and also of Being, in which all the stages of sense and knowledge are gathered up and from being hypotheses become realities. Leaving the comparison with Plato we may now consider the value of this invention of Hegel. There can be no question of the importance of showing that two contraries or contradictories may in certain cases be both true. The silliness of the so-called laws of thought ('All A = A,' or, in the negative form, 'Nothing can at the same time be both A, and not A') has been well exposed by Hegel himself (Wallace's Hegel), who remarks that 'the form of the maxim is virtually self-contradictory, for a proposition implies a distinction between subject and predicate, whereas the maxim of identity, as it is called, A = A, does not fulfil what its form requires. Nor does any mind ever think or form conceptions in accordance with this law, nor does any existence conform to it.' Wisdom of this sort is well parodied in Shakespeare (Twelfth Night, 'Clown: For as the old hermit of Prague, that never saw pen and ink, very wittily said to a niece of King Gorboduc, "That that is is"...for what is "that" but "that," and "is" but "is"?'). Unless we are willing to admit that two contradictories may be true, many questions which lie at the threshold of mathematics and of morals will be insoluble puzzles to us.