7. The Conscious Life of Man

Now exactly the same process takes place within our organism when we think. This corresponding process of thinking is a salt-depositing process, so to speak, which is caused by a certain activity in our blood and which irritates and reacts upon our nerve-system, a process, that is, which goes on on the “frontiers” between our blood- and nerve-systems. And just as we can look at the water in the glass and observe the formation of the salt as it separates and crystallises, so we may see, when we observe a human being exercising thought, that just such a process, supersensibly perceptible in all its exactness to the clairvoyant eye, actually does take place. Thus we have here brought before our minds the physical correlative of the process of thought.