Reasonable men therefore will look upon the general plan of our constitution, transmitted down to us by our ancestors, as sacred ; and content themselves with calmly doing what their station requires, towards rectifying the particular things which they think amiss, and supplying the particular things which they think deficient in it, so far as is practicable without endangering the whole.
From Six Sermons Preached on Public Occasions, Sermon III. The argument he gives for this conclusion is rather interesting because it is historical. This sermon was preached before the House of Lords on the day commemorating the martyrdom of Charles I. Charles, of course, lost his head to the Puritans. The sermon is primarily on the subject of hypocrisy, which seems to have interested Butler considerably, given that he returns to it in a number of sermons. The particular worry in this sermon is hypocritical appeal to liberty. Hypocrisy, of course, arises due to the fact that it is difficult to do something wrong as wrong, in its true colors; it's far easier to do it when "some cloak is thrown over it" to give it the appearance of virtue. Butler notes that there is a special danger of liberty being used as this cloak. This is what he suggests actually happened in the overthrow of Charles; people went so far as to destroy the very constitution of Church and State in the name of liberty, replacing it with "the confusions, the persecuting spirit, and incredible fanaticism" that led to the Restoration. This violent overthrow began innocently enough; but as more and more fuel was added to the fire, it quickly grew out of hand, growing more and more outrageous, until, in the name of liberty, it introduced an arbitrary despotism. This particular arbitrary government wasn't sustainable, being contrary to custom, but it led to a further danger when the Restoration occurred, because the monarchy was sustainable, and human beings in opposing one extreme are likely to go to the other. One extreme, the complete dissolution of the monarchy, was rejected; but going through that complete dissolution, and the reaction it induced, introduced the severe danger of going too far in the return of the monarchy, by eliminating the limitations originally restricting the king's power. Butler, then, has a very stern view of the dissolution of the monarchy; he thinks it was obviously wrong, so obviously wrong that no one could have done it innocently. But, of course, human beings are capable of great self-deceit. Even though it's plausible to say that a better government can be imagined, to go so far as to dissolve at one stroke one government that works in practice in favor of another government known only in theory is courting mischief. Thus we arrive at the conclusion above, and this provides one safeguard against the hypocritical abuse of liberty.
It isn't, by the way, the only abuse of liberty against which we need safeguards; Butler goes on to have an interesting discussion of some others, insisting throughout that liberty by its very nature requires self-command, and the responsibilities that go with that.