The student must be careful also nbt to conclude that he has necessarily failed because his melody differs from that given in the key for a large number of the basses given will carry many different melodies above them. As an illustration of this point, the author may mention that he some time since gave one of the basses in the additional exercises (no. 12 to Chapter XIII.) to several of his best pupils at the Royal Academy, with special directions to write as good a melody above it as they could. Five or six hymn-tunes were the result, no two of which resembled one another, while not one was identical with that in the key yet all were good tunes. The resources both of melody and harmony are practically inexhaustible, and it is to aid the student in exploring them that this key is published.