Sri Aurobindo
Letters of Sri Aurobindo
Volume IV - Part 3
It is the final discovery that one makes that in this world everything depends upon consciousness and its movements, even the things that seem not to do so. In these matters of illness, vital trouble etc., that resolves itself into suggestion (hostile) and 
auto-suggestion. Coué, though he did not know these things, had the brilliant intuition of adopting the contrary method of curative auto-suggestion and giving it a thorough and systematic application. Here it does not succeed so well because the anti-Coué spirit is very strong in many, the habit of entertaining hostile suggestions or this openness to them. Yet in Yoga also faith and right auto-suggestion are of great use until the point comes when no suggestion is necessary because the Truth-consciousness acts automatically and produces its natural results.