Octave Mirbeau book The Torture Garden
Variant: “It isn’t dying that’s sad. It’s living when you’re not happy.”
Source: Le Jardin des supplices

The Torture Garden is a novel written by the French journalist, novelist and playwright Octave Mirbeau, and was first published in 1899 during the Dreyfus affair. The novel is dedicated: "To the priests, the soldiers, the judges, to those people who educate, instruct and govern men, I dedicate these pages of Murder and Blood."
Octave Mirbeau book The Torture Garden
Variant: “It isn’t dying that’s sad. It’s living when you’re not happy.”
Source: Le Jardin des supplices