The high priest was required to offer up a special grain-offering every morning and every evening.
Channeling the Inner High Priest
וְהַכֹּהֵן הַמָּשִׁיחַ תַּחְתָּיו מִבָּנָיו יַעֲשֶׂה אֹתָהּ וגו': (ויקרא ו:טו)
The priest from among [Aaron’s] sons who is anointed [as high priest] must offer up [this grain-offering]. Leviticus 6:15

Our inner “high priest” is the innermost aspect and core of our soul, which is permanently bound to G‑d. This aspect of our soul is that part of us that refuses to participate in any act that is a denial of our connection with G‑d.

The classic example of something that disconnects us from G‑d is idolatry. But really, any violation of G‑d’s will can be considered a form of idolatry, for when we violate G‑d’s will we are serving something other than G‑d (whether it be money, fame, pleasure, or despair). If we would only realize this fact, nothing could entice us away from fulfilling G‑d’s will – whether by dwelling on unholy or depressing thoughts, by speaking unholy or insensitive words, or by performing unholy or destructive actions.

In this context, our personal “high-priestly” grain-offering is the meditative contemplation through which we channel the innermost core of our souls. Like the high priest’s offering, drawing upon the power of this core is necessary both in the figurative “morning,” i.e., when we feel enlightened and inspired, in order to ensure that we channel our energy in accordance with G‑d’s will, and in the figurative “evening,” i.e., when we feel confused or uninspired, in order to ensure that we resist the temptation to go against what we know we should be doing.1