My many weaknesses are starting to show their heads. I simply must get this out of my system. I'm not a writer. I've been fooling myself and other people. I wish I were.
- John Steinbeck, wrote in his journal on August 16, 1938, when he was writing Grapes of Wrath. As quoted in the book Working Days.

Much of what is termed “writer's block” is an artist's unable to overcome his or her insecurities, and his or her fear of how the work will be received. Is my work good enough? Am I good enough? The artist is paid, or not paid, as the case may be, to overcome those fears and work. Put it out there. Let it make its own way in life. Let, the consequences be what they may.

The most demanding part of Living a life as an artist is the strict discipline of forcing oneself to work along the nerve of one's own most intimate sensitivity.
- Anne, a sculptor from her book Daybook: The Journal Of An Artist

In 1907, Picasso painted his most controversial painting, Les Demoiselles Avignon, The Young Ladies of Avignon. It's of five nude female prostitutes in a brothel in Barcelona. They are painted with strange angles and profiles — harsh, unforgiving, almost threatening. Even his friends reacted negatively. Matisse, perhaps the most controversial painter in France, was reportedly “enraged” by the painting. It met such a strong reaction that Picasso hid it away for several years.

. . . no one could have been prepared for the shock of 1907's Le Demoiselles Avignon which many see as the most important painting of the century and one of the critical turning Points in the history of any art form.
- from Creating Minds by Howard Gardner

What I'd like to make you realize at once is the incredible heroism of a man like Picasso, whose moral loneliness was, a the time, quite horrifying, for none of his painter friends had followed him. Everyone found that picture crazy or monstrous.
-Daniel Henry Kahnweiler, art dealer

Picasso, after painting one of the most important paintings of the century, retreated from it. Picasso, a man legendary for his self-confidence and indifference to criticism and rejection, hid away one of the greatest paintings of history because other people found it repulsive. At first. Eventually, it expanded our conception of art. It expanded our imagination. Eventually, it prevailed. There's an important lesson there. You can't let the voices take over. You have to let it rip and roar. It is difficult. The possibility of failure is always staring you in the face. Artists who stick it out to the bitter end enlarge our vision of life, of courage, of potential Years after painting it, Picasso offered these thoughts:

A work of art must not be something that leaves a man unmoved, something he passes by with a casual glance. . . It has to make him react, feel strongly, and start creating too, if only in his imagination... He must be jerked out of his torpor. You have to wake people up. To revolutionize their way of identifying things. You've got to create images they won't accept.

An artist's insecurities are a double-edged sword. On the one hand, they can inhibit work, and discourage work. On the other, they can spur an artist into efforts of constant improvement, and constant experimentation.

If you're not insecure about your writing, you're either mailing in forgettable stuff or somebody else is writing for you.
-Harlan Coben