By letter or by word? Both quotations have the same total contrast energy. In the first the energy is divided equally among all the letters, making all the letters equally and independently identifiable. In the second quotation the energy is divided equally among all the words, regardless of their length. In principle, for a given noise level, a known pattern's detectability depends only on its energy, so equal energy words should be equally visible, but in fact the short words pop out and the long words disappear. This shows that human readers cannot efficiently integrate the energy across a whole word. Instead the word is identifiable only when its letters are independently identifiable. (The quotes are “In the beginning was the Word … And the light shineth in darkness.”)  Pelli, D. G., Farell, B., & Moore, D. C. (2003) The remarkable inefficiency of word recognition. Nature 423, 752-756. pdf http://psych.nyu.edu/pelli/