In the Name of Allah, the Most Gracious, the Most Merciful.
The Qur'an is a Reminder and a Revelation from Allah
We have already discussed the separated letters at the beginning of Surah Al-Baqarah, so there is no need to repeat its discussion here. Allah says,
مَآ أَنَزَلْنَا عَلَيْكَ الْقُرْءَانَ لِتَشْقَى
(We have not sent down the Qur'an unto you to cause you distress,) Juwaybir reported that Ad-Dahhak said, "When Allah sent the Qur'an down to His Messenger , he and his Companions adh- ered to it. Thus, the idolators of the Quraysh said, `This Qur'an was only reve- aled to Muhammad to cause him distress.' Therefore, Allah revealed,
وَمَا تَحْتَ الثَّرَىٰ (And whatever is beneath the soil - 20:6). (ثرٰی) (soil) means wet earth which comes out after digging upto a certain depth. Human knowledge does not go beyond) and what is beneath it is known only to Allah. Some years back scientists and researchers, using the latest and the most sophisticated instruments, spent considerable time and effort to pierce across the centre of the earth. According to newspaper reports they were able to penetrate upto a depth of six miles only after which they came across a rock casing and all their efforts to bore further down failed. Scientists were able to collect data only upto six miles, while the diameter of the earth covers thousands of miles. One has to admit, therefore, that the knowledge of what is below the soil is a special attribute of Allah.
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 6–7
The Quran is a reminder of the call to the Truth, but its full impact is felt only when the caller himself is fully dedicated to the cause of God, having sacrificed his own interests thereto. If he is to bring people to the right path, he must be seen to put others’ welfare before his own, even if this brings him toil and trouble. But no matter how perfect the presentation of the call to the Truth may be, only those will receive guidance from it who are capable of recognizing and appreciating the truth, and for whom the reasoned argument alone is enough to open their eyes. The August Being, who created the universe, has Himself revealed the Quran. Therefore, there is no contradiction between the Quran and nature. The Quran is a reminder of the truth. But its impact can only be commensurate with the ability —already innate in human nature—to recognise the truth.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.