“Several actual worlds without one another are not, therefore, impossible by the very concept, as Wolf hastily concluded from the notion of a complex or multiplicity which he deemed sufficient to a whole, as such, but only on condition that there exist but one necessary cause of all things. If several are admitted, several worlds without one another will be possible in the strictest metaphysical sense.”

Saraïde, in Book Seven : What Saraïde Wanted, Ch. XLVII : Economics of Saraïde
The Silver Stallion (1926)
Context: Life is a pageant that passes very quickly, going hastily from one darkness to another darkness with only ignes fatui to guide; and there is no sense in it. I learned that, Kerin, without moiling over books. But life is a fine ardent spectacle; and I have loved the actors in it: and I have loved their youth and high-heartedness, and their ungrounded faiths, and their queer dreams, my Kerin, about their own importance and about the greatness of the destiny that awaited them, — while you were piddling after, of all things, the truth!

The Dilemma of Determinism (1884) p.153
1880s

De Pace Fidei (The Peace of Faith) (1453)

Hegel, Philosophy of Mind (quoted by Slavoj Žižek in A Glance into the Archives of Islam http://www.lacan.com/zizarchives.htm, Lacan dot com, 1997).

Vol. I, Ch. 3: Of the vision of the Image composed of four Metals
Observations upon the Prophecies of Daniel, and the Apocalypse of St. John (1733)

Kant's Inaugural Dissertation (1770), Section IV On The Principle Of The Form Of The Intelligible World

De Anima ii 1, 412b6–9: About the Mind–body problem
De Anima

My Memories of Eighty Years (1922), p. 292

Kant's Inaugural Dissertation (1770), Section IV On The Principle Of The Form Of The Intelligible World