My own passion for nature is becoming uncontrollable. At times I look on animals and even trees with a tenderness that amounts to a feeling of affinity: I derive almost voluptuous sensations from the mere act of seeing — when I see clearly.

Letter to Alfred LePoittevin, 13 May 1845. As quoted in: The Letters of Gustave Flaubert: 1830-1857 (Harvard University Press, 1980)