The blue colour is also easy to understand. It also reflects the physiological and psychological need, namely: peace. Blue is a typical celestial colour. With great penetration, it develops the element of rest. Bending down to black, it acquires a shade of inhuman sorrow. It is like an endless deepening into a serious one, where there is no end and there can be no end. When looking at the dark blue colour comes vegetative calming. Pulse, blood pressure, respiration rate and waking function are reduced and regulated trophotropic. The body is adjusted to calm and rest. With disease and fatigue, the need for blue increases. It also increases susceptibility and readiness for pain. Dark blue - like each of the four basic colours - is a colour expression of one of the basic biological needs: physiologically - rest, psychologically - satisfaction. Who is in such a balanced, harmonious state without stress, feels in place: in close connection with the surrounding environment and safety. T