“Variety can destroy variety.”

Source: The evolution of socio-technical systems, (1981), p. 9

P 107
The Piano Teacher (1988)

The Rover, Part II, Act I (1681).

Book V, Chapter 4.
Books, Coningsby (1844), Vivian Grey (1826)

As quoted in The God Particle (1993) by Leon Lederman – ISBN 978–0–618–71168–0
Context: The progress of science is the discovery at each step of a new order which gives unity to what had long seemed unlike. Faraday did this when he closed the link between electricity and magnetism. Clerk Maxwell did it when he linked both with light. Einstein linked time with space, mass with energy, and the path of light past the sun with the flight of a bullet; and spent his dying years in trying to add to these likenesses another, which would find a single imaginative order between the equations between Clerk Maxwell and his own geometry of gravitation When Coleridge tried to define beauty, he returned always to one deep thought: beauty he said, is "unity in variety." Science is nothing else than the search to discover unity in the wild variety of nature — or more exactly, in the variety of our experience.

Melodia semplice e varietà nel ritmo.
His motto for Italian music, formulated in a letter to Filippo Filippi, August 26, 1868; Luca Somigli Legitimizing the Artist (2003) p. 103.
Often misquoted as "Simple melody – clear rhythm!"

Moses Mendelssohn, Briefe über die Empfindungen (1755)
Misattributed

Source: Discourses (1967), Vol. III, Ch. 1 : The Avatar, p. 11.
Context: CONSCIOUSLY or unconsciously, every living creature seeks one thing. In the lower forms of life and in less advanced human beings, the quest is unconscious; in advanced human beings, it is conscious. The object of the quest is called by many names — happiness, peace, freedom, truth, love, perfection, Self-realisation, God-realisation, union with God. Essentially, it is a search for all of these, but in a special way. Everyone has moments of happiness, glimpses of truth, fleeting experiences of union with God; what they want is to make them permanent. They want to establish an abiding reality in the midst of constant change.
It is a natural desire, based fundamentally on a memory, dim or clear as the individual’s evolution may be low or high, of his essential unity with God; for, every living thing is a partial manifestation of God, conditioned only by its lack of knowledge of its own true nature. The whole of evolution, in fact, is an evolution from unconscious divinity to conscious divinity, in which God Himself, essentially eternal and unchangeable, assumes an infinite variety of forms, enjoys an infinite variety of experiences and transcends an infinite variety of self-imposed limitations. Evolution from the standpoint of the Creator is a divine sport, in which the Unconditioned tests the infinitude of His absolute knowledge, power and bliss in the midst of all conditions. But evolution from the standpoint of the creature, with his limited knowledge, limited power, limited capacity for enjoying bliss, is an epic of alternating rest and struggle, joy and sorrow, love and hate, until, in the perfected man, God balances the pairs of opposites and transcends duality. Then creature and Creator recognise themselves as one; changelessness is established in the midst of change, eternity is experienced in the midst of time. God knows Himself as God, unchangeable in essence, infinite in manifestation, ever experiencing the supreme bliss of Self-realisation in continually fresh awareness of Himself by Himself.
This realisation must and does take place only in the midst of life, for it is only in the midst of life that limitation can be experienced and transcended, and that subsequent freedom from limitation can be enjoyed.