The final step was a big one and he slipped as he descended to the pavement.  Luckily, the bus driver, with a practiced preparedness, caught him on the way down, avoiding the inevitable crunch that would likely have occurred.  The older man bowed in appreciation, then went to the side of the bus to claim his rolling bag. For Duyi Koay, it had been some 15 years since he had been to Williamsburg.  His partial paralysis had made travel complicated and frequently painful, causing him to build his world around his studio outside of Clifton Forge.  A series of taxis waiting in a lengthy line provided a sense of relief as he ventured over to the leading vehicle. “Need a ride, sir?” the driver…