Of course, I was under-estimating the birthday card trade. If you put the quote into Google it comes up as is as one of the most quoted lines from Proust's tome of nearly one and a half million words. Every other person has posted it on their blog. It's certainly up for grabs. I'm curious about the translation, though. The original C. K. Scott Moncrieff translation of the French, 'L'amour c'est l'espace et le temps rendus sensibles au coeur' is pretty literal: 'Love, what is it but space and time rendered perceptible by the heart'. The Moncrief and Kilmartin translation, revised by D. J. Enright, is hardly different: 'Love is space and time made perceptible to the heart'. The active measuring heart on the birthday card -- where does it come from? Google doesn't say.
But context is everything. The line comes near the end of 'The Captive', where Marcel is torturing himself by imagining the lesbian adventures of his beloved Albertine. In the Enright revised translation, the preceding sentences read:
How many people, how many places (even places which did not concern her directly, vague haunts of pleasure where she might have enjoyed some pleasure, places where there are a great many people, where people brush against one) had Albertine -- like a person who, shepherding all her escort, a whole crowd, past the barrier in front of her, secures their admission to the theatre -- from the threshold of my imagination or of my memory, where I paid no attention to them, introduced into my heart! Now, the knowledge that I had of them was internal, immediate, spasmodic, painful. Love is space and time made perceptible to the heart. (p. 440)
If you look in the wonderful index in the' Guide to Proust', published at the end of volume six of the 1996 Vintage edition, it is possible to find some other great one liners about love. Why, I wonder, has nobody thought to put on the front of greeting cards, one of the following:
'Love is an incurable malady'
'To be harsh and deceitful to the person whom we love is so natural'
'... love, even in its humblest beginnings, is a striking example of how little reality means to us'