http://www.boston.com/ae/books/articles/2011/01/26/edward_lengel_provides_the_many_myths_of_washington/ In the Congressional Prayer Room at the Capitol there is a stained-glass window depicting George Washington on his knees, praying in the snow at Valley Forge. Similar images appeared on a 2-cent stamp in 1928 commemorating the 150th anniversary of the Valley Forge encampment, and on the 13-cent Christmas stamp in 1977. Despite those depictions, it is a story with “dubious origins,’’ writes Edward G. Lengel in “Inventing George Washington,’’ his account of the myths and legends that sprang up to breathe life into a symbolic figure. There is the chopping-down-the-cherry-tree fable, and the use of Grant Wood’s absurdist illustration on the book’s jacket alerts the…