The scientific mind is at first inclined to see in this phenomenon the mechanical effect of reduced air-pressure, due to the higher temperatures above the surface of the boiling mud, though doubts are raised by the unusual intensity of the reaction. The feeling that the physical explanation is inadequate is strengthened when the vapours have thinned out and one is surprised to see that every crack and cranny in the Solfatara, right up to the top of the trough, shows signs of increased activity. Certainly, this cannot be accounted for by a cause-and-effect nexus of the kind found in the realm of mechanical causation, where an effect is propagated from point to point and the total effect is the sum of a number of partial effects. It looks rather as if the impulse applied in one spot had called for a major impulse which was now acting on the Solfatara as a whole. As observers who are trying to understand natural phenomena by recognizing their significance as letters in nature's script, we must look now for other phenomena which can be joined with this one to form the relevant 'word' we have set out to decipher. All scientific theories concerning the causes of seismic occurrences, both volcanic and tectonic, have been conceived as if the spatial motion of mineral matter were the only happening that had to be accounted for. No wonder that none of these theories has proved really satisfactory even to mechanistically orientated thinking. Actually there are phenomena of a quite different kind connected with the earth's seismic activities, and these need to be taken into equal account. There is, for instance, the fact that animals often show a premonition of volcanic or tectonic disturbances. They become restive and hide, or, if domestic, seek the protection of man. Apparently, they react in this way to changes in nature which precede the mechanical events by which man registers the seismic occurrence. Another such phenomenon is the so-called earthquake-sky, which the present writer has had several occasions to witness. It consists of a peculiar, almost terrifying, intense discoloration of the sky, and, to those acquainted with it, is a sure sign of an imminent or actual earthquake somewhere in the corresponding region of the earth. This phenomenon teaches us that the change in the earth's condition which results in a violent movement of her crust, involves a region of her organism far greater than the subterranean layers where the cause of the purely mechanical events is usually believed to reside.6 That man himself is not excluded from experiencing directly the super-spatial nature of seismic disturbances is shown by an event in Goethe's life, reported by his secretary Eckermann, who himself learnt the story from an old man who had been Goethe's valet at the time.7