a paragraph from 'the weight of glory' by cslweis:

these things - the beauty, the memory of our own past - are good images of what we really desire; but if they are mistaken for the thing itself, they turn into dumb idols, breaking the hearts of their worshippers. For they are not the thing itself; they are only the scent of a flower we have not found, the echo of a tune we have not heard, news from a country we have never yet visited.

this has helped to work out the ache in my heart a little better.