It is obvious that this case, like that of the eminent painter just
referred to, borders closely on the hallucinations of the insane, and
Blake _did_ become insane subsequently. But usually there is nothing
abnormal or pathologic in the power of mentally recalling sights or
sounds, and it would be well if everybody cultivated this power. Mr.
Galton mentions an electrical engineer who was able to recall forms
with great precision, but not color. But after some exercise of his
color memory he became quite an adept in that, too, and declared that
the newly-acquired power was a source of much pleasure to him.

In music most of us have the power of recalling a simple melody; and
who has not been tormented at times by an unbidden melody persistently
haunting his ears until he was almost ready to commit suicide? But to
recall a melody at will _with any particular tone-color_, _i.e._, to
imagine it as being played by a flute, or a violin, or a horn, is much
less easy; and still more difficult is it to hear two or more notes
_at once_ in the mind, that is to recall harmonies. It is for this
reason that people of primitive musical taste care only for operas
which are full of "tunes." These they can whistle in the street and be
happy, while the harmonies and orchestral colors elude their
comprehension and memory. Consequently they call these works "heavy,"
"scientific," or "intellectual;" whereas if they took pains to educate
their musical imaginations, they would soon revel in the magic
harmonies of modern operas, with their infinite variety of gorgeous
orchestral colors.

Every student of music should carefully heed Schumann's advice.
"Exercise your imagination," he says, "so that you may acquire the
power of remembering not only the melody of a composition, but also