This coming Sunday, being Laetare Sunday, is the only day of Lent in which solo organ music is permitted. The temptation is to use something that fits with the character of laetare, such as Bach's Wir danken dir, Herr Jesu Christ, dass fuer uns gestorben bist. However, since this is the only day of Lent in which organ solos are allowed, it might be good to make use of other parts of the repertoire for the season of Lent. Bach's O Mensch, bewein' dein Suende gross is probably the foremost example. It's what I'll be playing this Sunday, along with, of course, Wir danken dir. See video below.