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• 2 · Nature
• 21 · the four elements, and ether, the fifth element

21D · water (one of the four elements)

• 21D0 · 'Acqua', 'Carro dell'acqua' (Ripa)
• 21D1 · spirit of water, nix, undine
• 21D2 · ice ~ state of water
• 21D3 · steam