happen that an investigator who possesses the power of vision in supersensible spheres may make mistakes in a logical presentment of them, and may be corrected by another who has no supersensible perception, but has, none the less, a capacity for sound thinking. In reality, nothing of any weight can be said against the logical deductions of occult science. And it ought to be unnecessary to insist that nothing can be adduced, on purely logical grounds, against the facts themselves. In the domain of the physical world it can never be proved by logic, but only by ocular demonstration, whether or no there is such an animal as a whale; similarly, supersensible facts can be known only through occult perception. But it cannot be sufficiently emphasized that an obligation is laid upon the explorer of supersensible regions, before he determines to approach the invisible worlds with his own power of perception, to acquire first of all the aforementioned logical faculty, and this is none the less essential if he recognizes that the world, manifest to his senses, will become comprehensible if he accepts the communications of occult science as correct. All experiences in the supersensible world are nothing but an uncertain—nay, a dangerous—groping in the dark if we despise the method of preparation which has been described. Therefore in this book the facts concerning the supersensible processes of the earth’s evolution will first be given, before the path leading to the attainment of supersensible knowledge is dealt with. We have also, it is true, to take into account that the man who, by sheer thinking, comes to accept what supersensible research has to impart, is by no means in the same position as one who listens to the account of a physical occurrence which he is unable to see. For thinking is in itself a supersensible activity. Materialistic thinking cannot of itself lead to supersensible phenomena. But if thought is directed to supersensible matters through the accounts given of them by occult science, it grows by its own activity into the supersensible world. What is more, one of the very best ways of acquiring supersensible perception is to grow into the higher worlds by meditation upon what has been communicated by occult science. For such a mode of entry insures great clearness of perception. For this reason such thinking is regarded by a certain school of occult investigation as a most valuable first step to take in occult training.