Humanity should be aware that they also live in the non-sensory, astral space at every moment of life. Just as sensory facts can be seen with physical eyes, in astral space, for example, a wish that comes to you can be seen flowing out like a cloud. Every wishful thought emanates from you like a force and flows out into astral space. Some thoughts have lightning-like shapes, and others resemble fine cloud images. Arrows or benevolent cloud shapes form through the force in the thoughts; rays and star shapes also arise. Everything takes shape and form. Everything is pliable (proteus-like), constantly changing shape and colour.
From the shape and colour, one can accurately discern what thoughts the human being sends into space. If you send a wrathful thought, it travels like a lightning bolt from you through the air up to the astral body of another human being; this can be perceived. It depends on the intensity of the wish, whether the thought shoots rapidly through astral space and on the character of the wishes in what colours they appear. Hot-headed, furious thoughts look brownish red to bloody red; thoughts of a quiet, calm, reflective, benevolent nature appear in a deep blue to violet colour. Shrewd, logical thoughts can be seen as yellow star shapes merging into each other. To consciously evoke such thought forms in astral space is what the spiritual student learns as he learns the laws of the astral and mental worlds. The neophyte knows precisely how the thoughts he sends into astral space work. That is clairvoyant development: becoming increasingly aware and conscious of these facts and sending out only thoughts that benefit humanity. That is one of the profound truths to which anthroposophy leads people.
Source (German): Rudolf Steiner – GA 88 – Über die astrale Welt und das Devachan – Berlin, 25 November 1903 (page 76/77)
Translated by Nesta Carsten-Krüger

Painting by Nesta Carsten-Krüger