The Conundrum of Section 133 CrPC - A Puzzle Unravelling

Yaar, I'm totally stuck on Section 133 of the CrPC. It talks about police inquiring into certain matters, but the definition of 'certain matters' is giving me sleepless nights. Section 133(1) says it's applicable when the police think it's necessary to make an inquiry, but what constitutes this necessity? The subsection says they must be inquiring into certain 'matters' or 'circumstances' but doesn't say what these 'matters' or 'circumstances' are. It's like they're playing hide and seek with the language. Then comes Section 133(2) which says the inquiry can even be initiated suo motu, which means the police have the power to start an inquiry on their own without any complaint or information. How does this reconcile with the whole necessity bit mentioned in Section 133(1)?