When you need a word that's deeper than "deep," consider profound. A philosopher is likely to make many profound pronouncements.
Profundus literally means "deep" in Latin, and profound had the same meaning when it entered English in the 14th century. But even then, it also meant "figuratively deep" — that is, very great or intense: "The new laws have had a profound impact." Of people, it means "very knowledgeable or insightful," but sometimes when a person tries to sound profound, they're really just giving you superficial knowledge dressed up with big words.