Mark Hobson has been citing lines from P H Emerson's "Naturalistic Photography" (found via T.O.P.). Here's some more:
But the artist sees deeper, penetrates more into the beauty and mystery of nature than the commonplace man.
no one can criticize any branch of art and the criticism be authoritative, unless he be a practical master artist in the branch of art which he is criticizing
The great heresy of 'sharpness' has lived so long in photographic circles ... for all through the lens has been considered purely from the physical point of view, the far more important physiological and psychological standpoints being entirely ignored
Remember, this was published in 1889.
I could blog for a month on this book and not run out of material. Go find a copy; read, re-read.