Akin to this argument are those which are based on man's desire of good. Proclus, in his 'Theology of Plato,' argues to the following effect: All beings desire the good; but this good cannot be identical with the beings which desire it, for then these beings would be themselves the good, and would not desire what they already possessed. The good is antecedent, therefore, to all the beings who desire it. Since the time of Proclus to the present many have argued that there must be a God because the heart demands one to satisfy its desire of love, or holiness, or happiness; few, perhaps, have done so with more ingenuity of logic or fervour of belief than John Norris in "Contemplation and Love, or the Methodical Ascent of the Soul to God by steps of Meditation," and in "An Idea of Happiness" ('Collection of Miscellanies').
A contemporary theologian, Principal Pirie of Aberdeen, has laid great stress on an argument which we may assign to this class. "No argument," he says, "can be valid which founds on innate ideas, or which embraces considerations so entirely beyond the range of human apprehension that we cannot positively be assured whether they be true or false. Yet we have no hesitation in saying that there is an argument _a priori_ for the existence and attributes of a God, which is involved in the very nature of our feelings, and which therefore tells upon the faith of the whole human race, even when they are altogether ignorant of it logically, as existing in the form of a proposition. It makes no appeal, however, to profound metaphysical speculations, and is consequently plain and intelligible to any one capable of exercising reason at all. It rests on the principle which both our feelings and our experience demonstrate to be true, that every primary and essential desire of the human mind has a co-relative--or, in other words, a something to gratify it--existing in the nature of things. The mode in which the development of this principle constitutes an argument _a priori_ for the existence and attributes of a God we now proceed to explain. Every human being feels from the moment in which he comes into existence, and through his whole subsequent history, that he is in himself a weak, helpless creature. As we have said, this feeling begins from the very beginning of our conscious existence. The appeals of the infant for aid are made continually.... As we advance to childhood, youth, and manhood, our sense of power gradually increases. We are conscious that under certain circumstances we can do something for ourselves. Yet this capability, we are also conscious in its very exercise, does not depend on us for its continuance. We cannot preserve to ourselves fortune, health, or even life, for _a single moment_. Yet all these things we desire, and desire with the utmost earnestness, and desire as a primary tendency of our minds. We may not indeed always clothe such desire in words--we may not put it into the form of a proposition; but that it exists in every mind as a feeling, and practically operates upon every individual, is as certain as our existence itself, and is indeed manifest every moment in the efforts which we make to preserve these and all other forms of what we believe to involve happiness. In this desire, consequently, we have the voice of nature speaking, and commanding us to use such efforts. Of ourselves we know that they would be insufficient. The results depend upon causes over which we have no control. Our own efforts, we are conscious, are only means which nature has appointed us to employ, but their success depends on circumstances altogether beyond our power. It is, as has been said, the voice of nature telling us that each of our desires has a co-relative, through which it may be fully gratified by the use of the proper means. This co-relative, in the case of intense and permanent happiness, can only be found in the existence of a God, omnipotent, omniscient, true, just, benevolent, and eternal, _in whom we repose entire confidence_. No other assumption could by possibility satisfy our desire for the highest and permanent happiness now and for ever. For to realise thoroughly the argument, it is to be observed that our desire is for the highest and permanent happiness. It is not imperfect or temporary happiness merely which we desire, though we may be compelled to be content with this, if we cannot procure more. It is the highest happiness possible for our natures, and that without end. Now, if such happiness is to be attained at all, it can only be obtained through a God possessed of the attributes which we have enumerated."--Natural Theology, pp. 71-74.