There are, first of all, two kinds of authors: those who write for the subject's sake, and those who write for writing's sake. ... The truth is that when an author begins to write for the sake of covering paper, he is cheating the reader; because he writes under the pretext that he has something to say.
...most men have bound their eyes with one or another handkerchief, and attached themselves to some one of these communities of opinion. This conformity makes them not false in a few particulars, authors of a few lies, but false in all particulars. Their every truth is not quite true. Their two is not the real two, their four not the real four; so that every word they say chagrins us, and we know not where to begin to set them right.
I would give them (aspiring writers) the oldest advice in the craft: Read and write. Read a lot. Read new authors and established ones, read people whose work is in the same vein as yours and those whose genre is totally different. You've heard of chain-smokers. Writers, especially beginners, need to be chain-readers. And lastly, write every day. Write about things that get under your skin and keep you up at night.
Sometimes he spent hours together in the great libraries of Paris, those catacombs of departed authors, rummaging among their hoards of dusty and obsolete works in quest of food for his unhealthy appetite. He was, in a manner, a literary ghoul, feeding in the charnel-house of decayed literature.