Besides Rudolf Steiner's fundamental insight into the spiritual-physical nature of the growing human being, through which he laid the basis of a true art of education, he gave advice on many practical points. For example, he indicated how by the choice of a suitable colour environment one can bring a harmonizing influence to bear on extremes of temperament in little children. To-day it is a matter of practical experience that excitable children are quietened if they are surrounded with red or red-yellow colours, or wear clothes of these colours, whereas inactive, lethargic children are roused to inner movement if they are exposed to the influence of blue or blue-green colours.