The concept of inner teacher or inner being has two different branches: the Platonism on the one hand and the Bible on the other.
According to the Philosophy of Plato the entities, that is, the beings; they belong to the sensible or physical world, for example the living beings and the objects; or to the intelligible world or world of ideas, to this world belong the genres and the essences, as "the beautiful", "the just", the soul.
From the first world we acquire knowledge through the physical senses, from the second we acquire knowledge through the contemplation of reason. For St. Augustine, who resume the ideas of Plato, the truths of the intelligible world are already somehow inside us, in that man or inner teacher.
San Agustin wrote: "About all the things we understand, it is not the speaker that resonates outside, but the truth that presides within the mind itself, which we consult, perhaps because we have been warned by the words to which we consult it. But the one who teaches is the one consulted, of whom it has been said that he dwells within the interior of man, Christ, that is, the immutable virtue and eternal wisdom of God. " Chapter XI, Book The Teacher.
St. Augustine also explained: "About the colors we consult the light ... about the things that are understood, we consult, instead, through reason, the inner truth", Chapter XII, The Master.
In the New Testament, the spirit is a grace and it is through this spirit that we receive the knowledge of the divine, the transcendent, the spirit is our inner teacher. The spirit is identified in the Old Testament with the propensity to acquire wisdom or science.
In the Gospels there are references to the inner teacher:"I pray that out of his glorious riches he may strengthen you with power through his Spirit in your inner being", Ephesians 3:16; also: "But you are not to be called Master, for you have one Teacher, and you are all brothers. And do not call anyone on earth father, for you have one Father, and he is in heaven. Nor are you to be called instructors, for you have one Instructor, the Messiah"; Matthew 23:8-9.