" . . . [O]ur soul has the power of representing to itself any form or nature whenever the occasion comes for thinking about it, and I think that this activity of our soul is, so far as it expresses some nature, form or essence, properly the idea of the thing."^1b

" . . . [T]he soul already includes the idea which is comprised in any particular thought."^1c

Correspondence with Arnauld. " . . . [T]he individual concept of each person includes once for all everything which can ever happen to him . . . "^1d

"In order to call anything possible it is enough that we are able to form a notion of it . . . "^1e

" . . . [N]othing happens without a reason . . . "^1f PLANCK

"A body is an aggregation of substances . . . 
Each of these substances contains in its nature the law of the continuous progression of its own workings and all that has happened to it and all that will happen to it."^1g SCHRODINGER

Monadology. "Our reasoning is based upon two great principles: first, that of Contradiction . . . And second, the principle of Sufficient Reason . . . There are also two kinds of Truths: those of Reasoning and those of Fact. The Truths of Reasoning are necessary, and their opposite is impossible. Those of Fact, however, are contingent, and their opposite is possible."^1h

"Today . . . when it has been learned through careful investigations made in plant, insect, and animal life, that the organic bodies of nature are never the product of chaos or putrefaction, but always come from seeds in which there was without doubt some preformation, it has been decided that not only is the organic body already present before conception, but also that a soul, in a word, the animal itself, is also in this body . . . "^1i* UPANISHADS SCHRODINGER BOHM
   

¹ G.W. Leibniz (1646-1716). Discourse on Metaphysics. Correspondence with Arnauld. Monadology. Introduction by Paul Janet. Translated by George Montgomery. Lasalle, IL: Open Court Publishing Company, 1902, 1995.
^a Discourse on Metaphysics, XIII, at 20.
^b Discourse on Metaphysics, XXVI, at 44.
^c Discourse on Metaphysics, XXIX, at 48.
^d Correspondence Relating to the Metaphysics, I Leibniz to Count Ernst von Hessen-Rheinfels, 1/11 Feb., 1686, at 69.
^e Correspondence, IX, at 131.
^f Correspondence, IX, at 132.
^g Correspondence Relating to the Metaphysics, XXVI Leibniz to Arnauld, Venice, March 23, 1690, at 244.
^h The Monadology, at 258.
ⁱ The Monadology, at 268.