1. It is in virtue of unity that beings are beings.
This is equally true of things whose existence is primal and of all that are in any degree to be numbered among beings. What could exist at all except as one thing? Deprived of unity, a thing ceases to be what it is called: no army unless as a unity: a chorus, a flock, must be one thing. Even house and ship demand unity, one house, one ship; unity gone, neither remains thus even continuous magnitudes could not exist without an inherent unity; break them apart and their very being is altered in the measure of the breach of unity.
Take plant and animal; the material form stands a unity; fallen from that into a litter of fragments, the things have lost their being; what was is no longer there; it is replaced by quite other things- as many others, precisely, as possess unity.
Health, similarly, is the condition of a body acting as a co-ordinate unity. Beauty appears when limbs and features are controlled by this principle, unity. Moral excellence is of a soul acting as a concordant total, brought to unity.
Come thus to soul- which brings all to unity, making, moulding, shaping, ranging to order- there is a temptation to say "Soul is the bestower of unity; soul therefore is the unity." But soul bestows other characteristics upon material things and yet remains distinct from its gift: shape, Ideal-Form and the rest are all distinct from the giving soul; so, clearly, with this gift of unity; soul to make things unities looks out upon the unity just as it makes man by looking upon Man, realizing in the man the unity belonging to Man.
Anything that can be described as a unity is so in the precise degree in which it holds a characteristic being; the less or more the degree of the being, the less or more the unity. Soul, while distinct from unity's very self, is a thing of the greater unity in proportion as it is of the greater, the authentic, being. Absolute unity it is not: it is soul and one soul, the unity in some sense a concomitant; there are two things, soul and soul's unity as there is body with body's unity. The looser aggregates, such as a choir, are furthest from unity, the more compact are the nearer; soul is nearer yet but still a participant.
Is soul to be identified with unity on the ground that unless it were one thing it could not be soul? No; unity is equally necessary to every other thing, yet unity stands distinct from them; body and unity are not identical; body, too; is still a participant.
Besides, the soul, even the collective soul for all its absence of part, is a manifold: it has diverse powers- reasoning, desiring, perceiving- all held together by this chain of unity. Itself a unity, soul confers unity, but also accepts it.