Why did Gabriel tell Muhammed to "Read" in cave hira when there was no reading material?

In a Nutshell:  The Prophet (saw) was illiterate, but the word read (اقرأ) here does not mean reading of any given text, rather it means to read the world like a book, to understand that it is full of signs pointing to its creator. The term iqra primarily refers to read however it can also alternative meanings of recite, repeat, read, utter, call and others. So, others have suggested it means reciting anything should commence with the name of Allah. Linguistic Meaning of Read (اقْرَأْْ) The Prophet (saw) received the first revelation in Hira cave (ghar). The first word of revelation was read. The Arabic term (قْرَأْْ) primarily refers to read however it can also alternative meanings of recite, repeat, read, utter, call and others. (Lisan al-Arab, al-Qamus al-Muhit) Considering the term read, its meaning comprises looking at, decoding and comprehending the meaning of written, visual or printed matter by interpreting the characters or symbols of which it is composed. Historic Context Regarding the first revelation in the cave A'isha (ra), the prophet's wife, narrated what happened: جَاءَهُ الْمَلَكُ فَقَالَ اقْرَأ ... فَقَالَ: ‏اقْرَأْ بِاسْمِ رَبِّكَ الَّذِي خَلَقَ * خَلَقَ الإِنْسَانَ مِنْ عَلَقٍ * اقْرَأْ وَرَبُّكَ الأَكْرَمُ‏.  "The angel came to him and asked him to read. … and then released me and said, 'Read in the name of your Lord, who has created (all that exists), created man from a clot. Read! And your Lord is the Most Generous." (Qur'an 96.1-3)" (Sahih al-Bukhari 3) This then led to 22 years of Qur'anic revelation. Analysis The term "read" is unqualified (mutlaq), nothing is specified, which would suggest Jibreel's command was for him to read anything he wished to. Should he do that he would do it with the name of God, its creator. The rest of the Qur'anic verses repeatedly emphasise the signs of God are everywhere, which if one was to read the world and whatever was in it like a book, with comprehension, they would see the signs, interpret them and realise the fingerprint of God, its creator, was everywhere. An alternative perspective is to consider the word iqra used in its metaphorical sense (majaazi). This is best illustrated when Muslims read the Qur'an from memory in the prayer, hadiths use the term read (اقرأ-قرأ) in reference to the recitation in the prayer. Thus the Prophet (saw) said to Mu'adh: يَا مُعَاذُ أَفَتَّانٌ أَنْتَ اقْرَأْ بِسُورَةِ كَذَا وَسُورَةِ كَذَا  "O Mu'adh, do you want to cause hardship to the people (in the prayer)? Recite (اقرأ) such and such a Surah, and such and such a Surah." (Sunan an-Nisa'i 835) Muslims also are required to seek the refuge of Allah against Iblis (Satan) whenever they recite the Qur'an whether by memory or when reading, but Allah says: فَإِذَا قَرَأْتَ الْقُرْآنَ فَاسْتَعِذْ بِاللَّهِ مِنَ الشَّيْطَانِ الرَّجِيمِ  "So when you recite (قرأت-read) the Qur'an, (first) seek refuge in Allah from Satan, the expelled (from His mercy)." (Qur'an 17:98) In another narration, the Prophet stated to his companions to recite a short chapter before when getting to sleep and it certainly recited from memory. The Prophet (saw) said: اقْرَأْ: قُلْ يَا أَيُّهَا الْكَافِرُونَ،‏ ثُمَّ نَمْ عَلَى خَاتِمَتِهَا فَإِنَّهَا بَرَاءَةٌ مِنَ الشِّرْكِ  "Read (اقرأ) (the Surah): 'Say, O you disbelievers!' (Surah No. 109) and then go to sleep at its end, for it is a declaration of freedom from polytheism." (Abi Dawud 5055) So Allah (swt) and His Prophet (saw) use the term read ( اقْرَأْ- قَرَأْتُ) where it refers to reciting. The Prophet (saw), in a similar situation, was teaching a companion a surah and this narration is very similar in terms or expression and conversation. Uqbah narrated: قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم لِعُقْبَةَ ‏"‏ اقْرَأْ ‏"‏ ‏.‏ قَالَ وَمَا أَقْرَأُ يَا رَسُولَ اللَّهِ قَالَ ‏"اقْرَأْ: قُلْ أَعُوذُ بِرَبِّ الْفَلَقِ، مِنْ شَرِّ مَا خَلَقَ‏"‏ ‏.‏ فَأَعَادَهَا عَلَىَّ حَتَّى قَرَأْتُهَا  "The Messenger of Allah (saw) said to Uqbah: 'Read.' He replied: 'What should I read, O Messenger of Allah?' He said: 'Read: 'Say: I seek refuge with (Allah) the Lord of the daybreak, from the evil of what He has created.' (Qur'an 113:1-2) And he repeated it until I had read it." (Sunan an-Nisa'i 5433) In this narration, the first three expressions for 'read' mean recite or repeat, but the last one means learned. So the word read (اقرأ) does not necessarily mean the literal reading but could mean repeat, recite, learn and others. Scholars' Views The mufassiroon generally agree the verse can mean read, recite, repeat or mention the name of your Lord with importance attached to commencing with or connecting the name of God. Imam Qurtubi said:  وَقِيلَ : مََعْنَى اِقْرَأْ بِاسْمِ رَبِّكَ أَيٌّ اُذْكُرْ اِسْمَهُ . أَمَرَهُ أَنْ يَبْتَدِئَ الْقِرَاءةَ بِاِسْمٍ اللَّهِ . "It has been said: the meaning 'read in the name of your Lord' is mention His name. He (Allah or Gabriel) ordered him to start recitation with the name of Allah." (Qurtubi, Tafseer al-Qurtubi, Vol. 20, p. 109) Imam al-Baghawi cites a statement of Abu Ubaydah (ra): قَالَ أَبُو عُبَيْدَةَ : مَجَازُهُ : اِقْرَأْ اِسْمَ رَبِّكَ يَعْنِي ... اُذْكُرْ اِسْمَهُ أَمَرَ أَنْ يَبْتَدِئَ الْقِرَاءةَ بِاِسْمٍ اللَّهِ تَأْدِيبًٱ "Abu Ubaydah said: it is a figurative (verse), as read in the name of your Lord means ... mention His name. (Allah) orders to begin the recitation with His name as a sign of politeness." (Baghawi, Tafseer al-Baghawi, Vol. 1, p. 477) Conclusion  The Prophet (saw) was illiterate, but the word read (اقرأ) here does not mean reading of any given text, rather it means to read the world like a book, to understand that it is full of signs pointing to its creator. The term primarily refers to read however it can also alternative meanings of recite, repeat, read, utter, call and others. So, others have suggested it means reciting anything should commence with the name of Allah. References Baghawi, Tafseer al-Baghawi Qurtubi, al-Jami li Ahkam al-Qur'an Ibn Mandhur, Lisan al-Arab Al-Qamus al-Muhit