Also, rearrangements. In two dimensions is easier. I cannot rearrange one pebble. I can rearrange two or three pebbles equidistant from each other in just on

Also, rearrangements. In two dimensions is easier. I cannot rearrange one pebble. I can rearrange two or three pebbles equidistant from each other in just one distinct way (inverting the position of a neighbouring pebble). And so on... There are many ways to think of natural numbers without actual numbers.