It is related from Ja’far ibn Muḥammad (may the peace and blessings of God be upon them both!) that he said:
“The Book of God has four things: literal expression (‘ibāra), allusion (ishāra), subtleties (laṭā’if), and deepest realities (ḥaqā’iq). The literal expression is for the common folk (‘awāmm), the allusion is for the elite (khawāṣṣ), the subtleties are for the friends of God (awliyā’), and the deepest realities are for the prophets (anbiyā’).
From Spiritual Gems: The Mystical Qur’an Commentary ascribed to Ja’far al-Sadiq as contained in Sulami’s Haqa’iq al-Tafsir ((Louisville: Fons Vitae, 2011), trans. Farhana Mayer, p. 1