“The author of the Gītā is interested in man and his destiny; for man is the centre of creation. Brahman, it is true, dwells equally in every living creature; but to man is given a gift denied even to the Lords of Heaven—man alone in all creation's scale can win release.”

This quote was attributed to Albert Schweitzer by Rachel Carson on p. 17 of her seminal work Silent Spring (1962), and is widely cited on various Internet websites, but an actual source from Schweitzer’s works is elusive.
Disputed

"Man alone, of all creatures of earth, can change his thought pattern and become the architect of his destiny." Actually said by Spencer W. Kimball, twelfth president of The Church of Jesus Christ of Latter-day Saints, in his Miracle of Forgiveness (1969), p. 114. This predates any of the misquotations.
Other forms: "The greatest discovery of my generation is that human beings can alter their lives by altering their attitudes of mind." This is also misattributed to Albert Schweitzer.
James did say: "As life goes on, there is a constant change of our interests, and a consequent change of place in our systems of ideas, from more central to more peripheral, and from more peripheral to more central parts of consciousness."
Misattributed

Inscription on monument

Source: What Men Live By (1881), Ch. IV
Context: Go — take the mother's soul, and learn three truths: Learn What dwells in man, What is not given to man, and What men live by. When thou hast learnt these things, thou shalt return to heaven.

Book V, line 527 (tr. J. D. Duff).
Pharsalia

Avot of Rabbi Natan (c. 700 – 900)
Misattributed

The Psychoanalysis of Fire, ch. 2, "Fire and Reverie" (1938)

Source: Sayings of Sri Ramakrishna (1960), p. 164
Context: Two friends went into an orchard. One of them possessing much worldly wisdom, immediately began to count the mango trees there and the number of mangoes each tree bore, and to estimate what might be the approximate value of the whole orchard. His companion went to the owner, made friends with him, and then, quietly going into a tree, began at his host's desire to pluck the fruits and eat them. Whom do you consider to be the wiser of the two? Eat mangoes. It will satisfy your hunger. What is the good of counting the trees and leaves and making calculations? The vain man of intellect busies himself with finding out the "why" and "wherefore" of creation, while the humble man of wisdom makes friends with the Creator and enjoys His gift of supreme bliss.

Hope, Despair, and Memory (1986)