Sulphur and phosphorus are thus seen to represent two polarically opposite tendencies with regard to the levity-gravity coherence which breaks up when combustion occurs. In the case of sulphur, the ponderable and imponderable entities appear to cling together; in the case of phosphorus, they seem to be anxious to part. These two different tendencies - which are characteristic of many other substances and represent a basic factor in the chemical happenings of the earth - are in their own way a pair of opposites. Since each of them represents in itself a relationship between two poles of a polarity-gravity and levity - so in their mutual relationship they represent a 'polarity of polarities'. In Fig. 4 an attempt has been made to represent this fact by a symbolic diagram. In this figure the shaded part represents the imponderable, the black part the ponderable entity. In the left-hand symbol both are shown in a relationship corresponding to the one characteristic of sulphur; in the right-hand figure the relationship is characteristic of phosphorus. Here we have an instance of a kind of polarity which belongs to the fundamentals of nature as much as does the levity-gravity polarity itself. Wherever two poles of a polarity meet, they have the possibility of being connected in two ways which in themselves are again polarically opposite. Our further studies will bring up various other instances of this kind, and will show us that part of the epistemological trouble in which science finds itself to-day results from the fact that the scientific mind has been unable to distinguish between the two kinds of polarity - that is, as we shall say henceforth, between polarities of the first order (primary polarities) and polarities of the second order (secondary polarities). In actual fact, the distinction between the two orders of polarity has been implicit in the descriptions given in this book right from the start. Remember, in this respect, how the picture of the threefold psycho-physical structure of man, which has proved a master-key for unlocking the most varied scientific problems, was first built up. There, 'body' and 'soul' represented a polarity which is obviously one of the first order. By our observation of the human organism, in relation both to the different functions of the soul and to the different main organic systems, we further recognized the fact that the ways in which body and soul are interrelated are polarically opposite in the region of the brain and nerves and in the region of the metabolic processes, which again results in two polarically opposite activities of the soul, mental on the one hand, and volitional on the other. In what we called the pole-of-consciousness and the pole-of-life we therefore have a clear polarity of the second order, and so in everything that is connected with these two, as our further discussions will show.