canon

In a canon, a melody is stated by one voice and then imitated exactly by one or more additional voices entering at staggered intervals. The simplest form is the round — like Row, Row, Row Your Boat — where each voice sings the same melody starting at different times. The canon reached its highest level of sophistication in the works of J.S. Bach, whose canons in The Musical Offering and The Art of Fugue demonstrate extraordinary contrapuntal ingenuity. Canons can be inverted, retrograde (backwards), or augmented (in longer note values), making them both an intellectual exercise and a beautiful musical form.