There are people so constituted that it is not possible for them to find the way to the Sprit, and to give them any proof of the Spirit will always be hard. They stick to something they know about, in accordance with their nature. Let us say they stick at something that makes the crudest kind of impression on them — Materialism. We need not regard as foolish the arguments they advance as a defence or proof of Materialism, for an immense amount of ingenious writing has been devoted to the subject, and it holds good in the first place for material life, for the material world and its laws.
Source: Rudolf Steiner – GA 151 – Human and Cosmic Thought: Lecture II – Berlin, 21st January 1910
Translated by Charles Davy