Why is a person unable to attain true attachment to God by means of his soul alone?
Why are qualities such as love and contemplation of the Divine incapable of effectuating “the dwelling of the Divine Presence”?
The qualities of the soul, whatever they may be, are unable to achieve an absolute fusion with the Divine resulting from the nullification of their own individual existence, as does oil that is consumed by fire.
Consequently, the soul on its own cannot achieve that level of contact with Ein Sof, it is incapable of attaining that degree of amalgamation with the One Truth besides which there is nothing else.
Rabbi Adin Steinsaltz