Complex sentence: Early in life, Humboldt had moments of temporary "religious fervour" which were brought up when he contemplated nature; when he grew up, "Humboldt acknowledged the existence of a rulling and regulative force in the world and said it could be called divinity".
Split into simpler sentences: Early in life, Humboldt had moments of temporary "religious fervour" which were brought up when he contemplated nature. When he grew up, "Humboldt acknowledged the existence of a rulling and regulative force in the world and said it could be called divinity".