David is a wonder-worker. He's completely remade Marat--from man into myth. For starters, Marat is bathed in light, which lends an angelic, other-worldly quality to him. All traces of the red, oozing scabs that thickly covered his skin are gone, an instance of 18th century air-brushing. Though he was killed by multiple stab wounds, inflicted on him by a woman named Charlotte Corday, only one is visible. That one, vertical slash--it's reminiscent of the spear wound painters have always shown in the side of Christ. It barely drips.
In fact, it's a very peaceful painting, isn't it? You could be almost forgiven for not thinking him dead. The only hint at violence is Corday's knife, lingering at the bottom of the painting; David's made it ashamed of its role in the great man's murder. Look closer though. You'll see that Marat is bathing in blood--the tub is full of it. Where is it all coming from? Well, David wants it both ways: He wants Marat the clean, pure secular saint; he also wants you to know what the great man has sacrificed for the French people.
How powerful is this art? From 1795-1846, or over fifty years, it did not see the light of day. The French monarchy, restored after Napoleon's final defeat in 1815, furiously sought it out. It was the ultimate Revolutionary painting; they wanted to obliterate it. From 1815-1848, under the reigns of Louis XVIII, Charles X and Louis-Phillippe, the painting was not safe in France.
Finally, why was Marat murdered? Two quotes encapsulate the tale. Before being guillotined by the regime, Charlotte Corday cried out that she had "killed one man to save one hundred thousand." The paper Marat grasps in the painting was a fake list of traitors Corday had brought to Marat in order to get close to him. Before she stabbed him to death, Marat glanced at the list, signed his name, and told her, "They shall all be guillotined."