However, to remove the apprehension that the soul may be dispersed by a wind, as it were, Socrates proceeds, in his third argument,[18] to examine that doubt more thoroughly.  What, then, is meant by being dispersed but being dissolved into its parts?  In order, therefore, to a thing being capable of dispersion it must be compounded of parts.  Now, there are two kinds of things—­one compounded, the other simple The former kind is subject to change, the latter not, and can be comprehended by the mind alone.  The one is visible, the other invisible; and the soul, which is invisible, when it employs the bodily senses, wanders and is confused, but when it abstracts itself from the body it attains to the knowledge of that which is eternal, immortal, and unchangeable.  The soul, therefore, being uncompounded and invisible, must be indissoluble; that is to say, immortal.

Still Simmias and Cebes[19] are unconvinced.  The former objects that the soul, according to Socrates’s own showing, is nothing but a harmony resulting from a combination of the parts of the body, and so may perish with the body, as the harmony of a lyre does when the lyre itself is broken.  And Cebes, though he admits that the soul is more durable than the body, yet objects that it is not, therefore, of necessity immortal, but may in time wear out; and it is by no means clear that this is not its last period.

These objections produce a powerful effect on the rest of the company; but Socrates, undismayed, exhorts them not to suffer themselves to be deterred from seeking the truth by any difficulties they may meet with; and then proceeds[20] to show, in a moment, the fallacy of Simmias’s objection.  It was before admitted, he says, that the soul existed before the body; but harmony is produced after the lyre is formed, so that the two cases are totally different.  And, further, there are various degrees of harmony, but every soul is as much a soul as any other.  But, then, what will a person who holds this doctrine, that the soul is harmony, say of virtue and vice in the soul?  Will he call them another kind of harmony and discord?  If so, he will contradict himself; for it is admitted that one soul is not more or less a soul than another, and therefore one can not he more or less harmonized than another, and one could not admit of a greater degree of virtue or vice than another; and indeed a soul, being harmony, could not partake of vice at all, which is discord.

Socrates, having thus satisfactorily answered the argument adduced by Simmias, goes on to rebut that of Cebes,[21] who objected that the soul might in time wear out.  In order to do this, he relates that, when a young man, he attempted to investigate the causes of all things, why they exist and why they perish; and in the course of his researches, finding the futility of attributing the existence of things to what are called natural causes, he resolved on endeavoring to find out the reasons of things.  He therefore assumed that there are a certain abstract beauty and goodness and magnitude, and so of all other things; the truth of which being granted, he thinks he shall be able to prove that the soul is immortal.