on sundays the church was a bright and airy place , the high vaulted roof , the stained glass windows streaming light , but in the gloom of thursday nights any sense of space was lost , there was a dark blanket like thunderclouds which weighed down on the penitents , and one by one they would enter the confessional , a dark box with wood panelled sides the colour of a wine cask , and speak their confessions through a fine mesh screen .