“If we want to transform reality, we begin with ourselves. We do not ask the world to change, and we do not fight against society. It has to be us ourselves who affirm our own values.”

Paraphrased variant: We do not need magic to change the world, we carry all the power we need inside ourselves already: we have the power to imagine better.
Harvard address (2008)

First Mansions, Ch. 1, as translated by E. Allison Peers (1961) p. 18
Interior Castle (1577)
Context: It is no small pity, and should cause us no little shame, that, through our own fault, we do not understand ourselves, or know who we are. Would it not be a sign of great ignorance, my daughters, if a person were asked who he was, and could not say, and had no idea who his father or mother was, or from what country he came? Though that is a great stupidity, our own is incomparably greater if we make no attempt to discover what we are, and only know that we are living in these bodies and have a vague idea, because we have heard it, and because our faith tells us so, that we possess souls. As to what good qualities there may be in our souls, or who dwells within them, or how precious they are — those are things which seldom consider and so we trouble little about carefully preserving the soul's beauty. All our interest is centred in the rough setting of the diamond and in the outer wall of the castle – that is to say in these bodies of ours.

Source: Christian Mystics (1999 - 2014), p. 8

Section III, Chap. I.
The Theory of Moral Sentiments (1759), Part II

"1860. In Lodge of Sorrow at Washington: March 30.", p. 11 <!-- [books.google.com/books?id=PTpRwZ1yEWwC&pg=PA11&dq=What+we+have+done+for+ourselves+Albert+Pike&hl=en&sa=X&ei=akWkT_3QCqLA6AHG_7G6CQ&ved=0CDcQ6AEwAA#v=onepage&q=remains immortal&f=false page 11] -->
In sentiment this is similar to the expression made much earlier by Giordano Bruno in On the Infinite Universe and Worlds (1584) : "What you receive from others is a testimony to their virtue; but all that you do for others is the sign and clear indication of your own."
Ex Corde Locutiones: Words from the Heart Spoken of His Dead Brethren
Variant: What we have done for ourselves alone dies with us; what we have done for others and the world remains and is immortal.

Prayer and the Art of Volkswagen Maintenance (2000, Harvest House Publishers)

Source: Irrational Man: A Study in Existential Philosophy (1958), Chapter One, The Advent of Existentialism, p. 3