Inscrutable
Inscrutable , adjective
[Latin inscrutabilis: compare French inscrutable. See In- not, and Scrutiny.]
Unsearchable; incapable of being searched into and understood by inquiry or study; impossible or difficult to be explained or accounted for satisfactorily; obscure; incomprehensible; as, an inscrutable design or event.
'T is not in man
To yield a reason for the will of Heaven
Which is inscrutable.
Waiving a question so inscrutable as this.