Lecture I

Then says the person in question: “Well, now we have an acute-angled triangle, a right-angled triangle and an obtuse-angled triangle. They certainly exist. But they are not the triangle. The collective or general triangle must contain everything that a triangle can contain. But a triangle that is acute-angled cannot be at the same time right-angled and obtuse-angled. Hence there cannot be a collective triangle. ‘Collective’ is an expression that includes the specific triangles, but a general concept of the triangle does not exist. It is a word that embraces the single details.”