“To accomplish great things we must not only act, but also dream; not only plan, but also believe.

(From an introductory speech at a session of the Académie Française, December 24, 1896)”

Understanding Islam, "Morals and Ethics" http://vod.dmi.ae/media/96716/Ep_03_Morals_and_Ethics Dubai Media

Source: Real Happiness: The Power of Meditation

Expression and Meaning, p. 31, Cambridge University Press (1979).

Source: The Butterfly as Companion: Meditations on the First Three Chapters of the Chuang-Tzu
Context: How do I know that enjoying life is not a delusion? How do I know that in hating death we are not like people who got lost in early childhood and do not know the way home? Lady Li was the child of a border guard in Ai. When first captured by the state of Jin, she wept so much her clothes were soaked. But after she entered the palace, shared the king's bed, and dined on the finest meats, she regretted her tears. How do I know that the dead do not regret their previous longing for life? One who dreams of drinking wine may in the morning weep; one who dreams weeping may in the morning go out to hunt. During our dreams we do not know we are dreaming. We may even dream of interpreting a dream. Only on waking do we know it was a dream. Only after the great awakening will we realize that this is the great dream. And yet fools think they are awake, presuming to know that they are rulers or herdsmen. How dense! You and Confucius are both dreaming, and I who say you are a dream am also a dream. Such is my tale. It will probably be called preposterous, but after ten thousand generations there may be a great sage who will be able to explain it, a trivial interval equivalent to the passage from morning to night.

Source: After Virtue (1981), p. 149.

Pour exécuter de grandes choses, il faut vivre comme si on ne devait jamais mourir.
Quoted in Queers in History: The Comprehensive Encyclopedia of Historical Gays (2009), by Keith Stern, p. 466.
Variant: In order to achieve great things, we must live as though we were never going to die.
Source: Reflections and Maxims (1746), p. 172.

Notebooks (1830).
1830s

Source: De architectura (The Ten Books On Architecture) (~ 15BC), Book II, Chapter IX, Sec. 14
Context: The larch... is not only preserved from decay and the worm by the great bitterness of its sap, but also it cannot be kindled with fire nor ignite of itself, unless like stone in a limekiln it is burned with other wood.... This is because there is a very small proportion of the elements of fire and air in its composition, which is a dense and solid mass of moisture and the earthy, so that it has no open pores through which fire can find its way... Further, its weight will not let it float in water.