Sri Aurobindo
Letters of Sri Aurobindo
06. Sadhana through Meditation
Fragment ID: 1389
Effort means straining endeavour. There can be an action with a will in it in which there is no strain or effort.
Straining and concentration are not the same thing. Straining implies an over-eagerness and violence of effort, while concentration is in its nature quiet and steady. If there is restlessness or over-eagerness, then that is not concentration.