Thus, consider the following three propositions: (i) The triangle has three angles, (ii) The substance exists, and (iii) The triangle exists. Proposition (i) is clearly self-explanatory, since the essence of the triangle (which contains the nature of the number three and the nature of an angle) is the sufficient reason for its having three angles (adding any other information is of no explanatory value). Spinoza considers proposition (ii) as self-explanatory as well. Notice that Spinoza does not