What is the meaning of all this?  Unless Shakespeare was out of his mind, it must have a meaning.  And certainly this meaning is not contained in any of the popular accounts of Iago.

Is it contained then in Coleridge’s word ‘motive-hunting’?  Yes, ‘motive-hunting’ exactly answers to the impression that Iago’s soliloquies produce.  He is pondering his design, and unconsciously trying to justify it to himself.  He speaks of one or two real feelings, such as resentment against Othello, and he mentions one or two real causes of these feelings.  But these are not enough for him.  Along with them, or alone, there come into his head, only to leave it again, ideas and suspicions, the creations of his own baseness or uneasiness, some old, some new, caressed for a moment to feed his purpose and give it a reasonable look, but never really believed in, and never the main forces which are determining his action.  In fact, I would venture to describe Iago in these soliloquies as a man setting out on a project which strongly attracts his desire, but at the same time conscious of a resistance to the desire, and unconsciously trying to argue the resistance away by assigning reasons for the project.  He is the counterpart of Hamlet, who tries to find reasons for his delay in pursuing a design which excites his aversion.  And most of Iago’s reasons for action are no more the real ones than Hamlet’s reasons for delay were the real ones.  Each is moved by forces which he does not understand; and it is probably no accident that these two studies of states psychologically so similar were produced at about the same period.

What then were the real moving forces of Iago’s action?  Are we to fall back on the idea of a ’motiveless malignity;’[114] that is to say, a disinterested love of evil, or a delight in the pain of others as simple and direct as the delight in one’s own pleasure?  Surely not.  I will not insist that this thing or these things are inconceivable, mere phrases, not ideas; for, even so, it would remain possible that Shakespeare had tried to represent an inconceivability.  But there is not the slightest reason to suppose that he did so.  Iago’s action is intelligible; and indeed the popular view contains enough truth to refute this desperate theory.  It greatly exaggerates his desire for advancement, and the ill-will caused by his disappointment, and it ignores other forces more important than these; but it is right in insisting on the presence of this desire and this ill-will, and their presence is enough to destroy Iago’s claims to be more than a demi-devil.  For love of the evil that advances my interest and hurts a person I dislike, is a very different thing from love of evil simply as evil; and pleasure in the pain of a person disliked or regarded as a competitor is quite distinct from pleasure in the pain of others simply as others.  The first is intelligible, and we find it in Iago.  The second, even if it were intelligible, we do not find in Iago.