In spite of folk wisdom to the contrary, there is no "three second rule" for copying or sampling recorded music. There is no rule that "four notes" can be copied without penalty. Instances under the fair use exception might include criticism or comment. Criticism need not be negative: if a jazz soloist quotes a phrase from a well-known solo by another player, it might be viewed as an homage. Music sampling has been aggressively pursued by copyright holders as a form of "free riding" but might be interpreted as a transformative use.