Visualiizing spacetime is ard when we try to imagine "a fourth direction
perpendicular to all the others." It may be easier when we try instead to
think about memory and anticipation as "directions." I have little trouble
looking at my child and at the same time grasping his/her infancy and
adulthood. The images aren't mushed together, either; their distinct, not
superimposed. I don't "see" it as the cliche child/adolescent/adult/senior
side-by-side, either, but truly "all at once."