Consider the case of a competent organist reading a fairly complicated item at sight; he has before his eyes three sets of five lines with curious marks on them, and the control of mechanism of a complex instrument in front of him, on both sides, and at his feet. Dealing with the marks on the staves he has to remember that one on a particular line or space means that he must put down a corresponding key, at a particular instant, accurate within a very few hundredths of a second. He has also to raise his fingers with equal accuracy. He has to remember that sharps or flats at the signature alter the meaning of the marks. He has to remember that the meaning of the marks is also affected by the clefs, and he has at least two of these. The area of paper that is sharply focussed on his retina is narrower than a single stave, so he has to read what is on the three, or perhaps four in little bits in advance, piecing them together at the right moment. When an Alpine mule comes to a rough piece he stops when it is under his nose and plans out his pedalling. He then goes on, and puts each foot precisely right on each bit of rock. But the organist may not stop. He has to arrange his fingering and pedalling in advance at full speed. He has to remember the positions of his stops, and must take his eyes off the print to change them or to change manuals; and as far as is possible in such a case, he has to arrange his stops in advance. But all this is the unmusical mechanical part of his work. He must realise what each passage means before he plays it; and when he plays it he must phrase it properly, adjusting the duration of his notes with extraordinary precision. If he is a very competent musician, he will appreciate the construction of the piece as he plays it, remembering the subjects, and following the modulations without forgetting the main key; and, if asked, he will transpose it all as he plays. While he is doing this, he may carry on a conversation about golf; but most likely he will not. This is one feat. Take another case; a man thinks out a symphony movement in the train and then writes out a full score to record on paper, in a complicated and ridiculous way, what he has produced in imagination, while his wife reads the paper to him.