It is neither speculation, nor a system of thought that has led us to a knowledge of the higher worlds; it is a beholding. Even as the development of the body, from the embryonic stage onwards, gives us a conception of the external physical world, so the steps described to you in principle (details can be found in the books I have mentioned) lead us to a knowledge of soul-processes and enable us to live in a spiritual world in which we existed before birth and into which we enter when we pass through the portal of death. Objective vision leads to a knowledge of the higher worlds.
Source: Rudolf Steiner – GA 79 – Paths to Knowledge of Higher Worlds – Christiania (Oslo), November 26, 1921