An artist must possess Nature. He must identify himself with her rhythm, by efforts that will prepare the mastery which will later enable him to express himself in his own language.

Matisse frames artistic originality as something earned through disciplined intimacy with the natural world. To “possess Nature” is not to copy it literally, but to internalize its underlying order—its “rhythm” of growth, movement, proportion, and balance. The artist studies and practices until these patterns become second nature (“mastery”), at which point expression can shift from imitation to a personal idiom (“his own language”). The quote also implies a paradox central to modern art: freedom and individuality arise from constraint and training, and the most personal style is grounded in a deep, patient apprenticeship to what is observed.