The lists of favorite things from you, gentle and gentlemanly readers, have been so excellent that I'm almost hesitant to move on to Part II. This is especially true because your approach to the things you list is so obviously free of wrong attitudes that Part II is inapplicable. And please don't feel that you must now abandon that thread for this one.
But here goes:
The question before us is this: If there are indeed things valuable in themselves, irrespective of any utilitarian value they may or may not have, how is it possible that a love of them and a devotion to them can be corrupting?
There are, unfortunately, all too many answers. One answer is that such a love can be corrupting when we fail to recognize a scale or hierarchy of values and are reckless of the ways in which the promotion of the valuable thing in question may harm other valuable things. An obvious example here is sex. Readers of other posts of mine know that I'm fond of paraphrasing a saying by Denis de Rougemont, cited by C.S. Lewis, "When Eros is made a god, he becomes a devil." The human wreckage of the sexual revolution speaks for itself of the dangers of idolizing one good at the expense of others. The fact that an act or an object is beautiful and wonderful in an intrinsic and non-utilitarian way never means that it is the most important thing or that it should be treated as the most important thing in life, and to do so risks unguessable harm, ultimately and paradoxically, to the beautiful thing itself.
Another and closely related answer is that such a love can be corrupting when we believe that the service of the valuable thing justifies us in doing acts we would normally regard as wrong. So, for example, eco-terrorism is wrong even if some animal species is truly beautiful and valuable.
A danger less drastic in its effects but perhaps more likely to fall upon the enthusiast for some valuable thing or activity is the temptation to theorize too much about the thing, to try to make one's enthusiasm for it part of some larger "movement," to do too much talking and moralizing. This danger is particularly prevalent in our blogospheric age of information, when everyone is tempted to theorize about everything. It isn't enough to love, say, good cooking and to engage in it and trade recipes. One has to make "____-food-ism" part of one's brand of conservatism and to write about how it fits into a political worldview. But as I said in the first post, it is the apolitical and focused nature of an enthusiasm for a valuable thing that is part of its charm, its glory, and its restfulness. While (to return to the earlier example) someone like Podhajsky wrote a great deal about his own ideas of dressage and the training of the young horse, about why traditional dressage is wonderful and beautiful and important, what you didn't find him doing (as far as I know) was writing about how his ideas on dressage fit into his large-scale world-view or political agenda and calling upon those who shared those politics to join him in advocating traditional dressage. He was too busy with the thing itself.
A less obvious form of potential corruption, because it lies on a continuum with an attitude that is not wrong, is the demand that others devote themselves to the same good and important thing to which one has devoted oneself. The list of intrinsically valuable things, if not infinitely long, is huge, especially if one differentiates the "things" at a fine-grained level. While one person may be captured by the some particular form of music, by architecture, or by the traditional liturgy, and may even rightly take it to be his own vocation to promote or preserve that thing, it does not follow that others have the same vocation.This much is obvious, and may seem trivial.
Moreover, it is obviously not wrong to (for example) teach about the beauty of that thing and even in some contexts to try to raise money for organizations that promote it or to ask for help. The Lippizzaners would never have been preserved for Austria if Podhajsky hadn't asked General Patton for help to support them and to return the mares from Czechoslovakia. So advocacy is not wrong. And an interesting question arises: Is not the best advocate the man consumed, the man who really does think that everyone else ought to see things as he does and ought to help? Someone with a better sense of perspective, with more balance and detachment, someone who says, "Well, I know that other people have a lot of other things on their minds, and I can't expect them to be as het up about this as I am" is unlikely to be able to drum up the support needed--in this all-too-pragmatic world--for the causes he cares about. And this is the more true when we are talking not about stopping manifest evils (e.g., abortion, sex trafficking) but rather about positively supporting some good that, in the final analysis, man could live without.
So I am quite sympathetic to the man who focuses on a single cause, especially when it's a cause I personally happen to be able to see the value of. (I get annoyed, of course, with those who are very passionate for causes I care little about.) But I cannot help thinking that he is in danger, regardless of the goodness of the thing. No doubt Podhajsky was in this danger, and no doubt somebody, sometime, said to him, "There's more to life than horses"--which he may have hotly denied. And that danger, to return to the first point above, is precisely to make the thing an idol. A sense of balance and perspective is, in the end, part of seeing things aright.
So let us love the good, the true, and the beautiful. And let us devote ourselves to them with a focused mind, a passionate heart, and, finally, with a clear eye. For the grace to see things in their proper order is one of the things valuable in itself, and one of the greatest of them all.