The ladder is symbol of an ascent from one stage to another.
What you felt was not imagination at all, but the usual experience one has when the consciousness is lifted out of the body and takes its stand above the head. One is no longer bound then by the physical consciousness or the sense of the body, the body becomes only an instrument, a small part of the consciousness which has to be perfected. One enters into a larger free spiritual consciousness in place of the present bound and limited physical consciousness. If this lifting up above the body can be repeated always until it can be maintained, it will be a great landmark in your progress. It is the confinement in the physical consciousness that makes you (and everybody) narrow and selfish and miserable. Hitherto the higher consciousness with its peace etc. has been descending into you with great difficulty and fighting out the vital and physical resistance. If this release upward into the higher consciousness can be maintained, then there will be no longer the same difficulty. Much will still remain to be done, but the foundation will have been made.