"Charles Dickens tells us every heart is a profound mystery to the heart beating nearest it." Don Miller
and if you're curious of the original quote like I was...
"A wonderful fact to reflect upon, that every human creature is constituted to be that profound secret and mystery to every other. A solemn consideration, when I enter a great city by night, that every one of those darkly clustered houses encloses its own secret; that every room in every one of them encloses its own secret; that every beating heart in the hundreds of thousands of breasts there, is, in some of its imaginings, a secret to the heart nearest it!" - Charles Dickens
just marinating on this little gem today.