Polyphony or multi-voiced music with each voice or instrument playing complimentary but different melodies at the same time was very fashionable in the 1500-1700's. Much of polyphony was imitative in nature such as canons or fugues. Motives or melodic ideas were imitated throughout the piece sometimes directly a few bars apart as in a Canon or even beginning on a different starting pitch as in a Fugue.
The simplest of this type of imitation canon is called a Round. Think of "Row Row Row Your Boat" or "Three Blind Mice." The short melody is faithfully imitated in three different voices one measure apart.
"For example, in The Musical Offering (a 1747 collection of mostly canons and fugues based on a theme given to him by Fredrick the Great), the “Crab Canon” is a single line of melody that acts as a retrograde canon (i.e., the melody played in reverse creates the counterpoint). Essentially, it’s a musical palindrome." (---quoted from Ian Davis in the FlyPaper)