“The Doctrine of a Perfect God; in whose nature nothing arbitrary or changeable can have a place; in whose Highest Being we all live, and in this Life may, and ought at all times to be, blessed;—this Doctrine, which ignorant men think they have sufficiently demolished when they have proclaimed it to be Mysticism, is by no means Mysticism, for it has an immediate reference to human action, and in deed to the inmost spirit which ought to inspire and guide all our actions. It can only become Mysticism when it is associated with the pretext that the insight into this truth proceeds from a certain inward and mysterious light, which is not accessible to all men, but is only bestowed upon a few favourites chosen from among the rest:—in which pretext the Mysticism consists, for it betrays a presumptuous contemplation of personal merit, and a pride in mere sensuous Individuality.”

Martí : Thoughts/Pensamientos (1994)

Notes from Devotional Authors of the Middle Ages (1873-1874)
Context: Where shall I find God? In myself. That is the true Mystical Doctrine. But then I myself must be in a state for Him to come and dwell in me. This is the whole aim of the Mystical Life; and all Mystical Rules in all times and countries have been laid down for putting the soul into such a state.
That the soul herself should be heaven, that our Father which is in heaven should dwell in her, that there is something within us infinitely more estimable than often comes out, that God enlarges this "palace of our soul" by degrees so as to enable her to receive Himself, that thus he gives her liberty but that the soul must give herself up absolutely to Him for Him to do this, the incalculable benefit of this occasional but frequent intercourse with the Perfect: this is the conclusion and sum of the whole matter, put into beautiful language by the Mystics. And of this process they describe the steps, and assign periods of months and years during which the steps, they say, are commonly made by those who make them at all.

Source: The Expanding Circle: Ethics, Evolution, and Moral Progress (1981), Chapter 4, Reason, p. 120

Beast and Man: The Roots of Human Nature (1979).

My Religion / Light in My Darkness, Ch 6 (1927)

44th Proposition, as translated by Mary Ilford in The Bourgeois: Catholicism vs. Capitalism in Eighteenth-Century France (1968), pp. 118-119

Book III, lines 549–550 (tr. James Michie)
Ars Amatoria (The Art of Love)

Source: Robinson Crusoe (1719), Ch. 1, Start in Life.

Christian Mysticism (1899), Preface
Context: The phase of thought or feeling which we call Mysticism has its origin in that which is the raw material of all religion, and perhaps of all philosophy and art as well, namely, that dim consciousness of the beyond, which is part of our nature as human beings. Men have given different names to these "obstinate questionings of sense and outward things." We may call them, if we will, a sort of higher instinct, perhaps an anticipation of the evolutionary process; or an extension of the frontier of consciousness; or, in religious language, the voice of God speaking to us. Mysticism arises when we try to bring this higher consciousness into relation with the other contents of our minds.