a letter from Henry James Sr. to his two sons

"Every man who has reached even his intellectual teens begins to suspect that life is no farce; that it is not genteel comedy even; that it flowers and fructifies on the contrary out of the profoundest tragic depths of the essential dearth in which its subject's roots are plunged. The natural inheritance of everyone who is capable of spiritual life is an unsubdued forest where the wolf howls and the obscene bird of night chatters."

Salman Rushdie quoting Henry James Sr. in his book The Satanic Verses, Chapter VII The Angel Azraeel.
According to Paul Brains's notes for The Satanic Verses:
The passage here quoted comes in fact from Henry James, Sr.’s book, Substance and Shadow (1866), p. 75. It is quoted in William James’ introduction to his father’s writings, collected in the volume entitled The Literary Remains of the Late Henry James (1884) but is not presented by him as a letter. The passage
is most readily available in Matthiessen (156). David Windsor points out that Rushdie evidently encountered the passage as the epigraph to José Donoso’s novel, The Obscene Bird of Night where the quotation is (mis-) attributed thus: “Henry James Sr., writing to his sons Henry and William.”