Selections from Augustine, On Christian Doctrine, on-line at Wheaton College, "The Christian Classics Ethereal Library,

2. All instruction is either about things or about signs; but things are learnt by means of signs. I now use the word "thing" in a strict sense, to signify that which is never employed as a sign of anything else: for example, wood, stone, cattle, and other things of that kind. Not, however, the wood which we read Moses cast into the bitter waters to make them sweet, nor the stone which Jacob used as a pillow, nor the ram which Abraham offered up instead of his son; for these, though they are things, are also signs of other things. There are signs of another kind, those which are never employed except as signs: for example, words. No one uses words except as signs of something else…

. There are some things, then, which are to be enjoyed, others which are to be used, others still which enjoy and use. Those things which are objects of enjoyment make us happy. Those things which are objects of use assist, and (so to speak) support us in our efforts after happiness, so that we can attain the things that make us happy and rest in them. We ourselves, again, who enjoy and use these things, being placed among both kinds of objects, if we set ourselves to enjoy those which we ought to use, are hindered in our course, and sometimes even led away from it; so that, getting entangled in the love of lower gratifications, we lag behind in, or even altogether turn back from, the pursuit of the real and proper objects of enjoyment.

4. For to enjoy a thing is to rest with satisfaction in it for its own sake. To use, on the other hand, is to employ whatever means are at one's disposal to obtain what one desires, if it is a proper object of desire; for an unlawful use ought rather to be called an abuse. Suppose, then, we were wanderers in a strange country, and could not live happily away from our fatherland, and that we felt wretched in our wandering, and wishing to put an end to our misery, determined to return home. We find, however, that we must make use of some mode of conveyance, either by land or water, in order to reach that fatherland where our enjoyment is to commence. But the beauty of the country through which we pass, and the very pleasure of the motion, charm our hearts, and turning these things which we ought to use into objects of enjoyment, we become unwilling to hasten the end of our journey; and becoming engrossed in a factitious delight, our thoughts are diverted from that home whose delights would make us truly happy. Such is a picture of our condition in this life of mortality. We have wandered far from God; and if we wish to return to our Father's home, this world must be used, not enjoyed, that so the invisible things of God may be clearly seen, being understood by the things that are made,--that is, that by means of what is material and temporary we may lay hold upon that which is spiritual and eternal.

20. Among all these things, then, those only are the true objects of enjoyment which we have spoken of as eternal and unchangeable. The rest are for use, that we may be able to arrive at the full enjoyment of the former. We, however, who enjoy and use other things are things ourselves. For a great thing truly is man, made after the image and similitude of God, not as respects the mortal body in which he is clothed, but as respects the rational soul by which he is exalted in honour above the beasts. And so it becomes an important question, whether men ought to enjoy, or to use, themselves, or to do both. For we are commanded to love one another: but it is a question whether man is to be loved by man for his own sake, or for the sake of something else. If it is for his own sake, we enjoy him; if it is for the sake of something else, we use him. It seems to me, then, that he is to be loved for the sake of something else. For if a thing is to be loved for its own sake, then in the enjoyment of it consists a happy life, the hope of which at least, if not yet the reality, is our comfort in the present time. But a curse is pronounced on him who places his hope in man. (Jer.17:5)

22. Those things which are objects of use are not all, however, to be loved, but those only which are either united with us in a common relation to God, such as a man or an angel, or are so related to us as to need the goodness of God through our instrumentality, such as the body. For assuredly the martyrs did not love the wickedness of their persecutors, although they used it to attain the favour of God. As, then, there are four kinds of things that are to be loved,--first, that which is above us; second, ourselves; third, that which is on a level with us; fourth, that which is beneath us…

26. Man, therefore, ought to be taught the due measure of loving, that is, in what measure he may love himself so as to be of service to himself…

28. Now he is a man of just and holy life who forms an unprejudiced estimate of things, and keeps his affections also under strict control, so that he neither loves what he ought not to love, nor fails to love what he ought to love, nor loves that more which ought to be loved less, nor loves that equally which ought to be loved either less or more, nor loves that less or more which ought to be loved equally. No sinner is to be loved as a sinner; and every man is to be loved as a man for God's sake; but God is to be loved for His own sake…

37. …For when the thing that we love is near us, it is a matter of course that it should bring delight with it. And if you pass beyond this delight, and make it a means to that which you are permanently to rest in, you are using it, and it is an abuse of language to say that you enjoy it. But if you cling to it, and rest in it, finding your happiness complete in it, then you may be truly and properly said to enjoy it. And this we must never do except in the case of the Blessed Trinity, who is the Supreme and Unchangeable God.

39. … The whole temporal dispensation for our salvation, therefore, was framed by the providence of God that we might know this truth and be able to act upon it; and we ought to use that dispensation, not with such love and delight as if it were a good to rest in, but with a transient feeling rather, such as we have towards the road, or carriages, or other things that are merely means…

40. Whoever, then, thinks that he understands the Holy Scriptures, or any part of them, but puts such an interpretation upon them as does not tend to build up this twofold love of God and our neighbour, does not yet understand them as he ought. If, on the other hand, a man draws a meaning from them that may be used for the building up of love, even though he does not happen upon the precise meaning which the author whom he reads intended to express in that place, his error is not pernicious, and he is wholly clear from the charge of deception…