What can be explained by the assumption of fewer things is vainly explained by the assumption of more things.

My God is the green tide in the spring leaves the redness of cherries high in the air the excitement of shooting stars the song of birds in summer branches the sunrise on a winter's morning the name of everything we don't understand.

With all things being equal, the simplest explanation tends to be the right one.

Entities must not be multiplied beyond necessity.

For nothing ought to be posited without a reason given, unless it is self-evident (literally, known through itself) or known by experience or proved by the authority of Sacred Scripture.

Intuitive cognition of a thing is cognition that enables us to know whether the thing exists or does not exist, in such a way that, if the thing exists, then the intellect immediately judges that it exists and evidently knows that it exists, unless the judgment happens to be impeded through the imperfection of this cognition.

It is vain to do with more what can be done with less.