“God spoke to Moses and said him, 'Now you will begin to see what I will do to Pharaoh.“
In order to receive prophecy, one needs to engage in contemplative meditation and to become a good and righteous person. There were schools of prophecy in Israel, and there has been a total of one-and-a-half million of prophets. Only the prophecies of the 24 prophets that were relevant to all times became canonized in the Writings.
When prophecy does come to a person, it comes from the “sapphire brick” under the feet of God. The Throne of Glory was seen as made of sapphire. The sapphire is blue, and it may be that they saw a vision of the sky as being below God. This stone is related to wisdom, and the Hebrew word sappir is related to sefer, a book. Some say that this 'sapphire' is like a 'third eye,' through which mystical vision is attained, and indeed, this third eye is associated with a sapphire blue color. It involves meditating on a single point and complete quietness of mind.
However, this is not the ultimate prophecy, since another name of the sapphire is “Glass that is not completely transparent.” The prophecy of Moses was from a higher world of Beriyah, the Word of Creation. The Sages say about Moses that he deserved to get Understanding, which is connected to the World of Beriyah, and to the Holy of Holies in the Temple.
The Torah phrase above hints to the different levels of God's communication with Moses. “God spoke to Moses” - Understanding. “And He said to him” - hints to the secrets of the highest Sefirah of Crown, or Will.
Art: John Singer Sargent - Blue Gentians