Of all the various constant and inconstant mental activities that different kinds of sentient beings can have
You should know that thoughts are like:
i) figures drawn on water, which instantly dissolve,
ii) or like drawings on sand, which are erased by different conditions,
iii) or like figures drawn on stone, which are indelible.
Where thoughts, either positive or negative, are like drawings on sand, this is of medium value.
Of these three cases, the first, where the thoughts are inconstant like figures traced on water, is the best as regards emotionally tainted thoughts.
As regards aspirations to undertake Dharma practice, the last, where the thoughts are stable like figures drawn on stone, is the best. So practice accordingly.
~ Kangyur Rinpoche
(Reference: padmamalla, Instagram, 4 July 2020)