Many people will say that such and such a poem or book or movie taught deep truths but then they never say what exactly they learn and I rarely challenge them since I suspect that they don't know. But I don't think they are kidding me since I have had the same impression from reading a great literary work. So is great literature more like music than actual philosophical discourse in its ability to convey ideas about life?

Very interesting! Consider two options, among others: one is that great literary works might be (as you suggest) akin to instrumental music. Such music may have emotive features (joy, anger, expressions of longing...) that are difficult to put into words and that is why your friends seem a bit weak in terms of their ability to state these deep truths. But secondly there might be deep truths that are not merely about emotions, but one finds hard to articulate because of a lack of vocabulary. Imagine one finds Tolkien's Lord of the Rings very moving and revealing but one cannot quite say why. Imagine (what seems likely) that Tolkien's trilogy raises questions about the ultimate meaning of life and the possibility of transcendent purpose, but that the reader is completely secular and has no vocabulary or training by which to put these matters into words.

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