273. Symbol No. 7 represents a stairway with steps of different sizes. From the previous symbol we have already become familiar with the middle row of steps representing life's six planes of existence or the six kingdoms. From the colours we see which basic energies form the basis of the kingdoms and from which they have their names. The evolution of living beings from a lower to a higher form of life is thus symbolised by those steps, which are expressing the fundamentally basic stages through which all living beings have to pass without exception. The colours show that the steps or stages repeat themselves so that every seventh step expresses the same basic energy - in other words when six zones of energy have been passed, the same zone is met once more. This means that each of the six different zones - that is, the plant kingdom, the animal kingdom, the human kingdom and so on - ranges endlessly from imperfection to perfection so that there is no limit to how imperfectly or perfectly such a kingdom can be manifested. But according to eternal laws which are not the result of previous thinking (to which we will return in later analyses), the development of living beings does not proceed permanently in each single kingdom, otherwise they would never be able to come out of the kingdom in which they found themselves at the time. Those living beings finding themselves in the animal kingdom would have to continue to be animals, and human beings would have to be human beings for ever; likewise plants and minerals would have to remain unchanged. But this is, of course, the opposite of life's actual condition when the spiritual faculty and cosmic sense are sufficiently developed, for then one realizes that the evolution of living beings goes through a section of the plant kingdom into the animal kingdom and having passed through a section of that kingdom goes further into the human kingdom and continues in this way until these living beings have passed through a section of all kingdoms. Then they pass smoothly into the plant kingdom again but now it is not into the same section as before but into a new section nearer to perfection in the same kingdom, and so on continually through all the kingdoms as before, but in each one always passing through new sections nearer to perfection. On the symbol those single steps will not express the whole domain of the basic energy whose colour they bear, but can express only a single section of that domain, while at the same time demarcating the relationship of that section to the sections of the remaining domains of the basic energies in the order in which they are passed through by the living being in the process of evolution.
      As each step of the same colour appearing on the middle row of steps thus expresses the same domain of basic energy - even though each has its own section - then on this account that row of steps will be defined as the "zones of the basic energies".