A gear box is a typical example of time.
there are many forward gears, a neutral position,
but only one reverse.

When we drive we are in the present looking to the future
but only occasionally refer to the past via the rear view mirror.
If we accidentally put the box in reverse while we are going forward the cogs will protest.

If we could apply this aspect of mechanics to the mind
we would discover that all movements of transmission
must pass through the neutral position.