“Ideas, unlike solid structures, do not perish. They remain immortal, immaterial and everywhere, like all Divine things.”

Нет бессмертия души, так нет и добродетели, значит, всё позволено. … Без бога-то и без будущей жизни? Ведь это, стало быть, теперь всё позволено, всё можно делать?
The Brothers Karamazov (1879–1880)

Allez! Tout fuit! Ma présence est poreuse,
La sainte impatience meurt aussi!
As translated by by C. Day Lewis
Charmes ou poèmes (1922)

Source: Talks for the Times (1896), "The Importance of Correct Ideals" (1892), p. 287

History of Religion and Philosophy in Germany, Vol. I (1834)

[Great applause.] But victory was worth nothing except for the truths that were under it, in it, and above it. We meet tonight as comrades to stand guard around the sacred truths for which we fought. [Loud and prolonged cheers.] And while we have life to meet and grasp the hand of a comrade, we will stand by the great truths of the war. ["Good," "good," and loud cheers.] Many convictions have sunk so deep into our hearts that we can never forget them. Think of the elevating spirit of the war itself. We gathered the boys from all our farms and shops and stores and schools and homes, from all over the Republic. They went forth unknown to fame, but returned enrolled on the roster of immortal heroes. [Great applause.] They went in the spirit of the soldiers of Henry at Agincourt, of whom he said. 'For he today that sheds his blood with me. Shall be my brother; be he ne'er so vile. This day shall gentle his condition.'
1880s, Speech to the 'Boys in Blue' (1880)

"The Immortal", § IV, in The Aleph (1949); tr. Andrew Hurley, Collected Fictions (1998)
Variant: To be immortal is commonplace; except for man, all creatures are immortal, for they are ignorant of death; what is divine, terrible, incomprehensible, is to know that one is immortal.

"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.

Source: https://independent.ng/2019debate-30-powerful-quotes-from-oby-ezekwesili-reactions-to-questions/ Oby Ezekwesili's reply to question during 2019 presidential debate.