Sri Aurobindo
Letters of Sri Aurobindo
Volume IV - Part 3
When the psychic puts its influence on the vital, the first thing you must be careful to avoid is any least mixture of a wrong vital movement with the psychic movement. Lust is the perversion or degradation which prevents love from establishing its reign; so 
when there is the movement of psychic love in the heart, lust or vital desire is the one thing that must not be allowed to come in – just as when strength comes down from above, personal ambition and pride have to be kept far away from it; for any mixture of the perversion will corrupt the psychic or spiritual action and prevent a true fulfilment.