“Isn't it a pleasure to study and practice what you have learned?”
The opening of the Analects and thus the first phrase of Chapter I after which the Chinese title of this book is named 學而.
The Analects, Chapter I
Context: Isn't it a pleasure to study and practice what you have learned? Isn't it also great when friends visit from distant places? If one remains not annoyed when he is not understood by people around him, isn't he a sage?
Original
學而時習之、不亦說乎。有朋自遠方來、不亦樂乎。人不知而不慍、不亦君子乎。
Help us to complete the source, original and additional information
Confucius 269
Chinese teacher, editor, politician, and philosopher -551–-479 BCRelated quotes

“Failing isn't bad when you learn what not to do.”

God doesn't believe in atheists (2002)

Source: It's Not Easy Being Green: And Other Things to Consider

His views on his multi-skills in p. 168.
Quote, Thought Leaders

Je ne sais point de plus grande finesse pour parvenir à aimer que d'aimer, comme on apprend à étudier en étudiant, à parler en parlant, à travailler en travaillant.
Francis de Sales, quoted in Vie de saint François de Sales, évèque et prince de Genève by André Jean Marie Hamon (Librairie Victor Lecoffre, Paris, 1896), Vol. II, Book VII, Ch. V: Son amour pour Dieu
Variant of sourced quotation: Comme on apprend à étudier en étudiant, à jouer du luth en jouant, à nager en nageant; aussi apprend-on à aimer Dieu et le prochain en l'aimant. — Francis de Sales, quoted in Jean-Pierre Camus, "L'esprit du bienheureux saint François de Sales" (1641), Part I, Section 31; published in Oeuvres complètes de saint François de Sales, ed. Jean-Irénée Depéry (Berche et Tralin, Paris, 1875), Vol. I
Misattributed