AC 3845 - seven, week; AC 3846 - serving, study

AC 3845
The reason why a "week," like all times specifically,
signifies a state and also a period,
is that all states have also their periods, that is:
their beginning, successive progress, and end;
yet in the other life these are not perceived as times,
but as states and their revolutions.
It is here very evident what the ancients understood by a week,
namely, . . . . every period that was distinguished into seven,
whether it was of days, or of years, or of ages;
whether it was great or small.
That here it is a period of seven years is clear;
and as with the ancients seven signified that which is holy,
a "week" signified a holy period,
and also the holiness of a period.

AC 3846
The reason why in the internal sense "serving" is study,
is that the labor of the external person
is study in the internal person.
Consequently, study is called a labor of the mind.