“The Buddha Fa” is an insight into all mysteries. It encompasses everything and leaves out nothing—from particles and molecules to the universe, from the even smaller to the even greater. It is an exposition of the characteristic of the universe, “Zhen-Shan-Ren,” (Truthfulness-Compassion-Forbearance) expressed at different levels with different layers of meaning. It is also what the Tao School calls the “Tao,” or what the Buddha School calls the “Fa.””

Section 8
Letter to a Priest (1951)
Context: Every time that a man has, with a pure heart, called upon Osiris, Dionysus, Buddha, the Tao, etc., the Son of God has answered him by sending the Holy Spirit. And the Holy Spirit has acted upon his soul, not by inciting him to abandon his religious tradition, but by bestowing upon him light — and in the best of cases the fullness of light — in the heart of that same religious tradition. … It is, therefore, useless to send out missions to prevail upon the peoples of Asia, Africa or Oceania to enter the Church.

Falun Buddha Fa Lectures in United States http://www.falundafa.org/book/eng/mgjf.htm

Source: Metamorphoses

"Shoaku makusa : Not Doing Wrong Action" http://wwzc.org/dharma-text/shoaku-makusa-not-doing-wrong-action as translated by Anzan Hoshin roshi and Yasuda Joshu Dainen roshi (2007)

Variant: The Tao that can be told is not the eternal Tao;
The name that can be named is not the eternal name.
The nameless is the beginning of heaven and earth.
Source: Tao Te Ching, Ch. 1, as translated by Ch'u Ta-Kao (1904)
Also as Tao called Tao is not Tao.
Context: The Tao that can be expressed is not the eternal Tao; The name that can be defined is not the unchanging name.
Non-existence is called the antecedent of heaven and earth; Existence is the mother of all things.
From eternal non-existence, therefore, we serenely observe the mysterious beginning of the Universe; From eternal existence we clearly see the apparent distinctions.
These two are the same in source and become different when manifested.
This sameness is called profundity. Infinite profundity is the gate whence comes the beginning of all parts of the Universe.

Source: Tao Te Ching, Ch. 1, as translated by J.H.McDonald (1996) http://www.wright-house.com/religions/taoism/tao-te-ching.html [Public domain translation]
Context: The tao that can be described
is not the eternal Tao.
The name that can be spoken
is not the eternal Name.
The nameless is the boundary of Heaven and Earth.
The named is the mother of creation.
Freed from desire, you can see the hidden mystery.
By having desire, you can only see what is visibly real.
Yet mystery and reality
emerge from the same source.
This source is called darkness.
Darkness born from darkness.
The beginning of all understanding.

Source: The Curious Incident of the Dog in the Night-Time

"Humanity", Ch.II "Ideologies: A way to live", Part I

Source: Bluebeard (1987), p. 188