I know Letters to a Young Poet, a work composed of letters by the poet Rainer Maria Rilke, is probably not very canonical but it does address philosophical and existential questions so I hope someone on this site might be able to help.
He mentions the word "Things", capitalized T. He first mentions it in letter 4 and here are some of the quotes:
" ...when I was in Paris, where everything echoes and fades away differently because of the excessive noise that makes Things tremble."
"But even so, I think that you will not have to remain without a solution if you trust in Things that are like the ones my eyes are now resting upon. If you trust in Nature, in what is simple in Nature, in the small Things that hardly anyone sees and that can so suddenly become huge, immeasurable;"
"...which speaks and chatters there (and how talkative it is!), and one slowly learns to recognize the very few Things in which something eternal endures that one can love and something solitary that one can gently take part in." "The situation you must live in now is not more heavily burdened with conventions, prejudices, and false ideas than all the other situations, and if there are some that pretend to offer a greater freedom, there is nevertheless none that is, in itself, vast and spacious and connected to the important Things that the truest kind of life consists of."
Does anyone know what these "Things" are, it seems they are some sort of metaphysical entities?