[Translated from the Pali by Thanissaro Bhikkhu.]
The Buddha said:
“There are these four unconjecturables that are not to be conjectured about, that would bring madness & vexation to anyone who conjectured about them. Which four?
“The Buddha-range of the Buddhas [i.e., the range of powers a Buddha develops as a result of becoming a Buddha] is an unconjecturable that is not to be conjectured about, that would bring madness & vexation to anyone who conjectured about it.
“The jhana-range of a person in jhana [i.e., the range of powers that one may obtain while absorbed in jhana]…
“The [precise working out of the] results of kamma…
“Conjecture about [the origin, etc., of] the world is an unconjecturable that is not to be conjectured about, that would bring madness & vexation to anyone who conjectured about it.
“These are the four unconjecturables that are not to be conjectured about, that would bring madness & vexation to anyone who conjectured about them.”
See also the Moggallana Sutta.