Domina omnium et regina ratio.
(M. Tullius Cicero, Tuscalanae Disputationes 2.21.47)

Reason is the mistress and the queen of all things.

Pron = DOH-mih-nah OHM-nee-oom et reh-GHEE-nah RAH-tee-oh

Comment: Cicero engages in some exploration of the human psyche, in
psychology, as we would call it centuries later. In this segment of
his Tusculan Disputations, he says that the human soul is divided into
two parts, one of which participates in reason and the other part
which does not. He describes reason as the mistress of the house, the
queen, in fact, who through struggle and progress finally becomes
virtue perfected.

This little snippet of a much longer work can be deceiving. It's not
that reason of itself is so grand. It's the struggling that reason
must do, if reason does that at all, within the human being. The
struggle produces courage (the other meaning of the Latin word
"virtue"). And, I suspect, whether Cicero says it or not, that this
struggle happens in the spaces between those two parts that make up
the human being: the part that participates in reason and the giant
silent one that does not.

We might notice that there is an inner dialogue, an inner struggle, a
swinging of the pendulum within us between a place that "reasons" and
a place that does not. There is no clean break between the two,
however much we might like to think that there is or could be. As
much as we might like the "clarity and cripsness" of reason, the
pendulum swings again into the irrational, dark, non-verbal parts of
us, and what it encounters there, it takes right back to reason. And
the inner conversation goes on.