Emptiness of emptiness

If we actually investigate something – any thing – we will find that it is made up of constituent parts that are not that thing.

And if we continue to investigate the constituent parts, we will find that they are made up of other constituent parts that are not them.

Such that we may eventually realise, perhaps there are only the appearance of characteristics which are dependent on causes/conditions. There were never any things or parts or constituents in the first place.

But what the heck are causes/conditions then?