[pessimizer]

And I'm pretty sure the Spanish matches (except in reverse, like Spanish usually is relative to English):

11:15 -> once y cuarto

11:30 -> once y media

11:45 -> doce menos cuarto

edit: and about the subject of the thread, "por sí" or "por sí mismo." "per" afaik is a preposition like "por" that means to pair or match things: so it can mean by, through, around, with, for, and even times("×") i.e. doesn't mean anything in English.

"si" is the 3rd person reflexive pronoun (when placed after the verb), and is probably similar to "se." ("mismo" is a redundant clarification is Spanish, probably because "si" and "sí" are homonyms.)

[asveikau]

Se and si (as used here) are the same word in different cases. I would draw comparisons to latin se and sibi respectively. I'd also draw parallels between sui, suus, secum and suyo, su, consigo.