A person appointed to act for another, a deputy; a substitute; a surrogate mother. In law, in some states, a surrogate is a judicial officer charged with probating wills and administering estates.
As an adjective, regarded as, or acting as, a surrogate.
Reading is merely a surrogate for thinking for yourself; it means letting someone else direct your thoughts. Many books, moreover, serve merely to show how many ways there are of being wrong, and how far astray you yourself would go if you followed their guidance. You should read only when your own thoughts dry up, which will of course happen frequently enough even to the best heads; but to banish your own thoughts so as to take up a book is a sin against the holy ghost; it is like deserting untrammeled nature to look at a herbarium or engravings of landscapes.
—Arthur Schopenhauer “On Thinking for Yourself” Essays and Aphorisms (1970)