6. Agnosticism in Science and Anthroposophy

But when we pass from abstract thinking to thinking in terms of reality, we must say the following. Let us take something that we construct mathematically within ourselves, for example, the sentence: If we draw a diameter in a circle and from one end of the diameter a line to any point on the circumference and from this point a further line to the other end of the diameter, then this angle is always a right angle. I do not need to draw this on the board at all. What I recognize there, namely that in a circle every angle through the diameter with the vertex on the periphery is a right angle, that is a purely internal experience. I have no need to use the circle here on the board.