These three are oddballs in philosophy and I have a hard time understanding what the big deal is. The first two whine and the last one spouts. Yet for some reason they are incessantly quoted or referred to. However if someone were to ask what was it uniquely Kierkegaardian, or Nietzschean, or even Schopenhauerian in the quote, I would really be at a loss for a definite answer. Well, maybe not Schopenhauerian. The man was a great observer, despite his sometimes embarrassing ideas.
Surely, I love Kierkegaard. It’s cool literature. Very passionate. But I fail to detect any depth in Frygt og bæven for example. These variations on Abraham’s story are perhaps inspirational in some sense, but I just do not see the book as philosophically significant. Nor do I see anything as all that significant. Yes, there is the idea of Existenz. But would Jaspers and Heidegger not have reached it on their own? What is there of Kierkegaard in either, except the word itself? For both it means something entirely different than what it means for Kierkegaard who just uses the fact that a Subject exists to more or less fetishize it. (All in good way, of course, just not really philosophically original. Yes, I interpret everything my way. Yes, study, relationship with God are among things deeply personal. Yes, I cannot make judgements about others without making judgements about myself. And so?)
Either inability to comprehend or open adversity to Hegelian ideas? Perhaps, as Jon Stewart compellingly shows, neither but just an axe to grind with Danish Hegelians.
If I were to single something of absolute importance it would be the ethical necessity in aesthetics. Or, to generalize, the importance of ethics in everything. Without that no philosophy is worth anything, and any intellectual or creative activity is worthless if it does not make us better, gentler human beings.