Again, the freedom of a creature must mean freedom to choose: and choice implies the existence of things to choose between. A creature with no environment would have no choices to make: so that freedom, like self-consciousness (if they are not, indeed, the same thing), again demands the presence to the self of something other than the self.
The minimum condition of self-consciousness and freedom, then, would be that the creature should apprehend God and, therefore, it'self as distinct from God. It is possible that such creatures exist, aware of God and themselves, but of no fellow-creatures. If so, their freedom is simply that of making a single naked choice - of loving God more than the self or the self more than God. But a life so reduced to essentials is not imaginable to us. As soon as we attempt to introduce the mutual knowledge of fellow-creatures we run up against the necessity of 'Nature'.
People often talk as if nothing were easier than for two naked minds to 'meet' or become aware of each other. But I see no possibility of their doing so except in a common medium which forms their 'external world' or environment. Even our vague attempt to imagine such a meeting between disembodied spirit's usually slips in surreptitiously the idea of, at least, a common space and common time, to give the co- in co-existence a meaning: and space and time are already an environment. But more than this is required. If your thoughts and passions were directly present to me, like my own, without any mark of externality or otherness, how should I distinguish them from mine? And what thoughts or passions could we begin to have without objects to think and feel about? Nay, could I even begin to have the conception of 'external' and 'other' unless I had experience of an 'external world'? You may reply, as a Christian, that God (and Satan) do, in fact, affect my consciousness in this direct way without signs of 'externality'. Yes: and the result is that most people remain ignorant of the existence of both. We may therefore suppose that if human souls affected one another directly and immaterially, it would be a rare triumph of faith and insight for any one of them to believe in the existence of the others. It would be harder for me to know my neighbour under such conditions than it now is for me to know God: for in recognising the impact of God upon me I am now helped by things that reach me through the external world, such as the tradition of the Church, Holy Scripture, and the conversation of religious friends. What we need for human society is exactly what we have - a neutral something, neither you nor I, which we can both manipulate so as to make signs to each other. I can talk to you because we can both set up sound-waves in the common air between us. Matter, which keeps souls apart, also brings them together. It enables each of us to have an 'outside' as well as an 'inside', so that what are acts of will and thought for you are noises and glances for me; you are enabled not only to be, but to appear: and hence I have the pleasure of making your acquaintance.
Society, then, implies a common field or 'world' in which it's members meet. If there is an angelic society, as Christians have usually believed, then the angels also must have such a world or field; something which is to them as 'matter' (in the modern, not the scholastic, sense) is to us.
But if matter is to serve as a neutral field it must have a fixed nature of it's own. If a 'world' or material system had only a single inhabitant it might conform at every moment to his wishes - 'trees for his sake would crowd into a shade'. But if you were introduced into a world which thus varied at my every whim, you would be quite unable to act in it and would thus lose the exercise of your free will. Nor is it clear that you could make your presence known to me - all the matter by which you attempted to make signs to me being already in my control and therefore not capable of being manipulated by you.
Again, if matter has a fixed nature and obeys constant laws, not all states of matter will be equally agreeable to the wishes of a given soul, nor all equally beneficial for that particular aggregate of matter which he calls his body. If fire comforts that body at a certain distance, it will destroy it when the distance is reduced. Hence, even in a perfect world, the necessity for those danger signals which the pain-fibres in our nerves are apparently designed to transmit. Does this mean an inevitable element of evil (in the form of pain) in any possible world? I think not: for while it may be true that the least sin is an incalculable evil, the evil of pain depends on degree, and pains below a certain intensity are not feared or resented at all. No one minds the process 'warm - beautifully hot - too hot - it stings' which warns him to withdraw his hand from exposure to the fire: and, if I may trust my own feeling, a slight aching in the legs as we climb into bed after a good day's walking is, in fact, pleasurable.
Yet again, if the fixed nature of matter prevents it from being always, and in all it's dispositions, equally agreeable even to a single soul, much less is it possible for the matter of the universe at any moment to be distributed so that it is equally convenient and pleasurable to each member of a society. If a man travelling in one direction is having a journey down hill, a man going in the opposite direction must be going up hill. If even a pebble lies where I want it to lie, it cannot, except by a coincidence, be where you want it to lie. And this is very far from being an evil: on the contrary, it furnishes occasion for all those acts of courtesy, respect, and unselfishness by which love and good humour and modesty express themselves. But it certainly leaves the way open to a great evil, that of competition and hostility. And if souls are free, they cannot be prevented from dealing with the problem by competition instead of courtesy. And once they have advanced to actual hostility, they can then exploit the fixed nature of matter to hurt one another. The permanent nature of wood which enables us to use it as a beam also enables us to use it for hitting our neighbour on the head. The permanent nature of matter in general means that when human beings fight, the victory ordinarily goes to those who have superior weapons, skill, and numbers, even if their cause is unjust.
We can, perhaps, conceive of a world in which God corrected the results of this abuse of free will by His creatures at every moment: so that a wooden beam became soft as grass when it was used as a weapon, and the air refused to obey me if I attempted to set up in it the sound-waves that carry lies or insults. But such a world would be one in which wrong actions were impossible, and in which, therefore, freedom of the will would be void; nay, if the principle were carried out to it's logical conclusion, evil thoughts would be impossible, for the cerebral matter which we use in thinking would refuse it's task when we attempted to frame them. All matter in the neighbourhood of a wicked man would be liable to undergo unpredictable alterations. That God can and does, on occasions, modify the behaviour of matter and produce what we call miracles, is part of Christian faith; but the very conception of a common, and therefore stable, world, demands that these occasions should be extremely rare. In a game of chess you can make certain arbitrary concessions to your opponent, which stand to the ordinary rules of the game as miracles stand to the laws of nature. You can deprive yourself of a castle, or allow the other man sometimes to take back a move made inadvertently. But if you conceded everything that at any moment happened to suit him - if all his moves were revocable and if all your pieces disappeared whenever their position on the board was not to his liking - then you could not have a game at all. So it is with the life of souls in a world: fixed laws, consequences unfolding by causal necessity, the whole natural order, are at once limit's within which their common life is confined and also the sole condition under which any such life is possible. Try to exclude the possibility of suffering which the order of nature and the existence of free wills involve, and you find that you have excluded life it'self.
As I said before, this account of the intrinsic necessities of a world is meant merely as a specimen of what they might be. What they really are, only Omniscience has the data and the wisdom to see: but they are not likely to be less complicated than I have suggested. Needless to say, 'complicated' here refers solely to the human understanding of them; we are not to think of God arguing, as we do, from an end (co-existence of free spirit's) to the conditions involved in it, but rather of a single, utterly self-consistent act of creation which to us appears, at first sight, as the creation of many independent things, and then, as the creation of things mutually necessary. Even we can rise a little beyond the conception of mutual necessities as I have outlined it - can reduce matter as that which separates souls and matter as that which brings them together under the single concept of Plurality, whereof 'separation' and 'togetherness' are only two aspects. With every advance in our thought the unity of the creative act, and the impossibility of tinkering with the creation as though this or that element of it could have been removed, will become more apparent. Perhaps this is not the 'best of all possible' universes, but the only possible one. Possible worlds can mean only 'worlds that God could have made, but didn't'. The idea of that which God 'could have' done involves a too anthropomorphic conception of God's freedom. Whatever human freedom means, Divine freedom cannot mean indeterminacy between alternatives and choice of one of them. Perfect goodness can never debate about the end to be attained, and perfect wisdom cannot debate about the means most suited to achieve it. The freedom of God consists in the fact that no cause other than Himself produces His acts and no external obstacle impedes them - that His own goodness is the root from which they all grow and His own omnipotence the air in which they all flower.