Art historian Lorna Cahall explores influential artists and art movements in A6’s monthly “Cheers to Art!” program. This month we toast William Blake.  A one-of-a-kind seer, prophet, social critic, artist, and poet, Blake managed to “see eternity in a grain of sand.” He experienced the huge upheaval of the 19^th century-the slow birth of modern times-before many of the breakthrough artists we look at-but he belongs with all of the artists who grappled with those changes.