How did God reveal Himself and communicate His will to the people of ancient Israel and Judea? A glance through the several books of the Old Testament would quickly suggest that God used various and several modes of divine self-disclosure towards His Old Covenant people through patriarchs, spokesmen, prophets as well as kings. This observation is encapsulated in a brilliant summary statement on Divine revelation by the author of the new Testament letter to the Hebrews in his prologue:
One such mode of Divine communication was through the awesome event of a Theophany. Among the most celebrated Theophanies to the ancient Israel one would include God's powerful descent on Mount Sinai as well as His majestic appearance to the prophet Isaiah in the Temple in Jerusalem. Another mode of Divine revelation was through dreams.
The Old Testament records that God chose to communicate His will to the people of Israel through the vehicle of dreams or "visions of the night" to certain selected persons. One such type of Divine dream is the co-called incubation dream. These are dreams initiated by God to the sleeping dreamer in holy places, without the recipient having deliberately sought to receive such a dream. Perhaps the most celebrated example of an incubation dream is Jacob's dream of the Divine ladder at Bethel (Gen 28:11-19):
Divinely-sent dreams, as recorded in the Old Testament, may be accompanied by declarations either: (i) in plain words understandable to the recipient, or (ii) in symbolic language or images needing an inspired interpreter. An instance of the former type of dream occurs in God's command to the grieving Jacob (Joseph's father) to travel to Egypt (Gen 46:1-4). Such a dream needed no interpretation. An example of the latter type is the Egyptian Pharaoh's two enigmatic God-sent dreams of the seven thin cows eating the seven fat cows grazing by the Nile as well as that of the seven withering ears of grain swallowing the good ears of grain, demanding a skilled interpreter of divine dreams - the wrongly-imprisioned Joseph:
The Old Testament however does not classify all dreams as God-sent. Indeed the elect of God receive very few dreams. On the other hand many dreams are considered as false. These are the dreams of the falser prophets, men who do not speak for God, and those dreams were not initiated by the Lord:
The use of dreams - as an instrument of Divine communication and the plan for human salvation - continues into the New Testament era. Thus within the Infancy narratives as recorded by St. Matthew, the righteous Joseph is the recipient of several dreams concerning: (i) the nature of the forthcoming Virgin Birth (Matt 1:20-21), (ii) a warning to flee to the safety of Egypt with Jesus and His Mother in the face of the Herodian massacre (Matt 2:13), (iii) an eventual call to return to the land of Israel (Matt 2:20), as well as instruction to settle in Galilee (Matt 2:22). Furthermore, the day of Pentecost is understood by the Apostles as a fulfillment of Joel's eschatological prophecy. In addition to the outpouring of the Holy Spirit, one further aspect of this prophecy deals with he expectation that while there shall be an increase in spiritual visions there shall also be a predisposition for the elderly to experience holy dreams:
"And it shall come to pass afterward, that I will pour out my spirit on all flesh; your sons and your daughters shall prophesy, your old men shall dream dreams, and your young men shall see visions. Even upon the men-servants and maid-servants in those days, I will pour out my spirit" (Joel 2:28-29).
Nevertheless, it is important to note that from an Orthodox theological or doctrinal position, the use of dreams after the Christ event is not necessarily for the purpose of adding further to the deposit of "revelation" or Sacred Truth as revealed in the Gospel of Jesus Christ, but rather a means of "illumination". Henceforth Jesus Christ, the Divine Word made flesh, becomes par excellence the exclusive mode of Divine revelation to the world. Nothing more can be added beyond Christ. Everything else which possesses truth is either inspired interpretation or illumination but not revelation! Thus while God may still send dreams to holy people they are not intended to add to the dogma of the Church but as a means of encouragement, warning or edification.