How heavy are thoughts?
Where are their roots?
It is not uncommon to hear in the spiritual circle phrases like "the 'I' is just a thought" or "thought is empty and spacious, there is no weight or root to it".
While the rootlessness and the space-like nature of "thoughts" should be pointed out, one must not be misled into thinking they have seen through "anything" much less up-rooted the deeply seated conceptual notions of "I/mine", "body/mind", "space/time"...etc.
So emphasis must also be placed on the other side of the coin. "Thoughts" are astonishingly heavy like a black-hole (size of a pinhole, weight of a star); the roots of conceptual notions" they carry permeate our entire being and everywhere.
The "roots" of thoughts are no where to be found also means they can be found anywhere and everywhere, spreaded across the 3 times and 10 directions -- in modern context, over different time-lines across the multiverse. In other words, "this arises, that arises".