The historian Daniel Walker Howe identifies "balance" as a dominant characteristic of the Harvard Unitarians of the 19th century (his book "The Unitarian Conscience: Harvard Moral Philosophy, 1805-1861" is required reading for understanding the Boston Unitarians,)
One of my favorite BU Sermons is James Walker's (see posts Walker) "The Daily Cross" which is an admirable application of the idea of balance to the Christian requirement of self-denial. Some excerpts:
"And he said unto them all, If any man will come after me, let him deny himself, and take up his cross daily, and follow me" Luke 9:23
"Never was the earnest inculcation of this precept more needed than at the present day. Surrounded, as many Christians now are, by ease, security, and abundance, they are tempted not only to neglect the self-denying virtues, but almost to forget their obligations and the important place they hold in the Christian life..that we are frequently called upon to submit to self-denial not from necessity but from choice, or, in other words, to take up our cross voluntarily, and to take it up daily, is not so generally conceded...What, then, is meant by that self-denial which is so frequently enjoined upon all men, in the New Testament ? Everyone is required to take up his cross daily; but what to crucify ?
Every one must be conscious of being under the influence of two orders of propensities and desires: the higher, or those which belong to him as a rational and moral being; and the lower, or those which belong to him as a sensual and selfish being. Even the lower tendencies of our nature are not bad in themselves ; they are bad only when they interfere with the proper development, or with the proper gratification, of the higher. Here then it is, that Christian self-denial begins and ends ; we are to deny the solicitations of our lower nature, whenever they interfere with the aspirations of our higher nature. Christian self-denial does not require us to deny our nature as a whole, but only to be true to our nature as a whole ; that is, to take care that the rightful subordination amongst its various springs of action shall be maintained. Christian self-denial does not require us to deny our happiness; that is to say, our highest happiness ; but only to be true to that happiness, by repressing every appetite or passion which puts itself in opposition to it, or which tends to frustrate or endanger it.
...the moral value of self-denial consists in its tendency to bring about this discipline : to teach every part of our nature to know its place, and keep its place, and thus to co-operate harmoniously and spontaneously in promoting the highest good of the individual. The moral value of self-denial does not consist in the pain it costs, but in its tendency to induce a habit of virtue, under the influence of which the practice of virtue will become agreeable and easy; so as, in the end, that is to say in heaven, to dispense with the necessity of self-denial altogether.
Self-denial, therefore, is not an end but a means; the end being to convert, through the power of habit, a painful and constrained obedience into a joyful and free obedience. The highest form of virtue is not the virtue of self-denial, but of earnest and irrepressible love; when duty has ceased to be a task and become a pleasure, a kind of necessity. Hence that sublime doctrine of the New Testament. " Whosoever is born of God doth not commit sin, for his seed remaineth in him; and he cannot sin, because he is born of God."