III. To a young gentleman who wished to devote himself to
literature as a profession 504

IV. To an energetic and successful cotton manufacturer 513

V. To a young Etonian who thought of becoming a cotton-spinner 522

PART XII.

SURROUNDINGS.

I. To a friend who often changed his place of residence 530

II. To a friend who maintained that surroundings were a matter
of indifference to a thoroughly occupied mind 539

III. To an artist who was fitting up a magnificent new studio 546

THE INTELLECTUAL LIFE.

PART I.

_THE PHYSICAL BASIS._

LETTER I.

TO A YOUNG MAN OF LETTERS WHO WORKED EXCESSIVELY.

Mental labor believed to be innocuous to healthy persons--Difficulty
of testing this--Case of the poet Wordsworth--Case of an eminent
living author--Case of a literary clergyman--Case of an energetic
tradesman--Instances of two Londoners who wrote
professionally--Scott's paralysis--Byron's death--All intellectual
labor proceeds on a physical basis.

So little is really known about the action of the nervous system, that
to go into the subject from the physiological point of view would be to
undertake a most difficult investigation, entirely beyond the competence
of an unscientific person like your present correspondent. You will,
therefore, permit me, in reference to this, to leave you to the teaching
of the most advanced physiologists of the time; but I may be able to
offer a few practical suggestions, based on the experience of
intellectual workers, which may be of use to a man whose career is
likely to be one of severe and almost uninterrupted intellectual labor.

A paper was read several years ago before the members of a society in
London, in which the author maintained that mental labor was never
injurious to a perfectly healthy human organization, and that the
numerous cases of break-down, which are commonly attributed to excessive
brain-work, are due, in reality, to the previous operation of disease.

This is one of those assertions which cannot be answered in a sentence.
Concentrated within the briefest expression it comes to this, that
mental labor cannot produce disease, but may aggravate the consequences
of disease which already exists.

The difficulty of testing this is obvious; for so long as health remains
quite perfect, it remains perfect, of course, whet