If we consider the natural world and mere worldly prudence, we find that parts of our lives are natural trials or states of probation preparing us for greater goods later. Some of our actions bring pleasure, some of our actions bring pain, and we are capable, through experience, of developing the foresight to weigh these outcomes. Thus we find that in order to get what we really want we must often discipline ourselves when it comes to what is right in front of us. We subjugate our present interest to a greater future interest. Because of this, however, we clearly can make sense of the idea that our lives taken as a whole might well be probationary in themselves:
Thus mankind having a temporal interest depending upon themselves, and a prudent course of behaviour being necessary to secure it, passions inordinately excited, whether by means of example, or by any other external circumstance, towards such objects, at such times, or in such degrees, as that they cannot be gratified consistently with worldly prudence, are temptations, dangerous and too often successful temptations, to forego a greater temporal good for a less; i.e. to forego what is, upon the whole, our temporal interest, for the sake of a present gratification. This is a description of our state of trial in our temporal capacity. Substitute now the word future for temporal, and virtue for prudence, and it will be just as proper a description of our state of trial in our religious capacity; so analogous are they to each other.
Butler argues that the analogy is quite strong, and that it gives to the notion of life as a state of moral and intellectual probation an antecedent credibility: it makes sense to see life in this way. Our life is a state of maturation and refinement in virtue, one with three aspects: trial or difficulty, opportunity for discipline, and the manifesting of our genuine moral character. And once we posit the idea that our life is probationary, we find a lot in our lives that fits it to be probationary; indeed, Butler argues, even more that makes it appropriate as a moral state of probation than makes parts of it appropriate as natural states of probation. He doesn't want to say that moral trial, a probationary period for building up virtue, is the whole of life; but it is a key part of life, and one of which we can make a remarkable amount of sense.