One of the reasons those three words got my attention was because they are basically the procedure that is advised many times throughout the essays on PureDhamma. How it’s not about mere book knowledge of the material or merely reading about Tilakkhana, but actually staying away from dasa akusala and doing necessary bhavana 24/7 not just during formal sessions, so that one can get to niramisa sukha to be able to truly grasp/absorb Tilakkhana in the mind.
The way I see it, is that a puthujjana needs pariyatti and paṭipatti to get to paṭivedha(magga phala, the Sotapanna stage).