Spinoza arrived at this position by way of a decidedly uncartesian account of attributes. While Descartes held that two substances of the same type can share the same principal attribute, Spinoza rejected this. Any two substances, argued Spinoza, must be distinguished either by their attributes (Spinoza dropped the modifier “principal”) or by their modes. But, since modes are themselves both ontologically and causally dependent on the substances of which they are affections, they cannot be the i