ability to multiplex - duality and non-duality

It seems the ability to multiplex thoughts seems to come naturally, except for some periods when there is a single thought. It also seems that that period of uninturrepted flow occurs only after repeatedly trying to do work and at the same time, keeping the "other" thoughts on God. This is probably what Shankara said when duality leads us to non-duality. And the Quote in PUM "The Lords's feet lead us to the other side".