Prophet Muhammad's biographies whether by Arabic authorities or even by foreign ones have unquestionably confirmed that he (pbuh) was of a highly reflective turn of mind (The Sealed Nectar/Ibn Hesham's "Prophetic Biography"/ Encyclopedia Britannica). In an authentic saying "hadith" by Al-Bukhary, the prophet's wife, Aisha, depicts an essential part of the Prophet's meditative character before being revealed to:

"…then seclusion has been endeared to him, and he was alone spending plenty of nights in Hiraa Cave extolling God i.e., praising and worshiping Him for long before retuning to his family to provide for another round… until the angel came to him".

Muhammad (pbuh) thus believed the universe has a creator whose power and signs can be seen and verified by reflecting upon life and world surroundings. He thus never believed those idols worshiped in Mecca then to be gods; never did he believe in plurality of gods. His intuition and meditations have always assured him that there is only one God to the universe; it is a situation, I believe, that reminds of the Prophet Abraham's stance with his early-life people:

"He said: what! Worship you that which you carve?! And God created you and what you do!" (Quran:Chapter 37; verses 95,6)

It seemed– as Al-Aqaad maintains in his "Muhammad's Genius"– that God had been preparing both the universe for receiving the Prophet (pbuh) and the Prophet for receiving a divine message. The Prophet was thus reported to be having true visions that always came true next days (The Sealed Nectar).

By the age of 40 in the cave,Hiraa, a majestic being (whom the prophet knew later as the angel Gabriel) came to Muhammad (pbuh) who was astounded by the event. The angel ordered the prophet thrice: "Read" and the prophet asked: "What should I read?" The angel then replied:

"Read in the name of your Lord Who created…" (Quran:chapter 96: verse 1; consider Ibn Hajar's "Fath Al-Bari").

He ran soon to his wife Khadijah who soothed him, taking him to her cosine Waraka who had a wide knowledge of the Scriptures. He told them the majestic being was the angel Gabriel who used to carry divine revelations down to the earth, to Moses and to all former prophets.

The angel disappeared for a few days until the prophet longed for him (The Sealed Nectar) and furthermore felt distressed for his absence. But he began to hear a voice saying to him,

"You are the Messenger of God" (ibid). It wasn't so long until Gabriel came again to the prophet, calling out to him for shouldering the responsibility of conveying a heavy divine message: "O (you) wrapped in your mantle. Arise and warn. And your Lord glorify…" (Quran: chapter 74: verses 1-3).