The form of our self-consciousness is not space but only time: this is why our thinking does not, like our intuition, occur in three dimensions, but only in one, and thus in a line without breadth or depth. This gives rise to the greatest of the fundamental imperfections of our intellect. Namely, we can have cognition of things only successively and can be conscious only of one thing at a time, and in fact this one thing only under the condition that we forget everything else in the meantime, that is, have no consciousness of anything else, so that nothing else exists for us during this time. In this respect, our intellect can be compared to a telescope with a very narrow field of vision, because our consciousness is not lasting but transient. The intellect apprehends things only successively and must leave one thing behind in order to grasp another, retaining only ever fainter traces of what is left behind. The thought that engages me keenly now will necessarily have entirely slipped my mind in a little while: and if I get a good night's sleep in between, then I might never find it again unless I have some personal interest in it, i.e. it is connected to my will, which always carries the day.

This imperfection of the intellect is the basis for the rhapsodic and often fragmentary character of our train of thought, which I already mentioned at the end of the previous chapter, and gives rise to the inevitable scattering of our thoughts. Sometimes external sense impressions disturb and interrupt our thinking and keep forcing complete irrelevancies upon it, and sometimes one idea will bring in another through the ties of association and be displaced by it; and finally, sometimes the intellect itself will not be able to sustain one single idea for very long, but be rather like the eyes when, after staring for a long time at a single object, they no longer see it very clearly since the edges run together and become confused and everything finally becomes obscure – similarly, when constantly pondering a single topic for a long period of time, thinking gradually becomes confused and blunted and ends up completely stupefied.