“You have to laugh,” Horace (Mark Prendergast) says to Arnolphe (Peter Forbes), the antagonist of Molière’s play, newly translated into rhyming couplets by the Scots Makar Liz Lochhead and revived by Tony Cownie for the Royal Lyceum Theatre in Edinburgh this spring. This adage is repeated twice more, and the audience must take comfort in it. The world of Educating Agnes is disturbing, devoid of human feeling, and the only coping mechanism for both the audience and the characters is to laugh. The Royal Lyceum Theatre in Edinburgh is perfectly suited to taking on this type of 17th-century drama, both in atmosphere and sheer theatrical clout.