[Skull]

There is a test by which one can make
certain whether something that springs into
the mind comes from the Higher Self, or
whether it is merely from some desire or
colored by some desire. Here is your test,
and an easy one. The Higher Self is impersonal;
it is self-forgetful; it is kind; it is
loving; it is pitiful; it is compassionate; it
has sublime inspirations.

From Golden Precepts of Esotericism by Purucker