The deep things of God

And I was with you in weakness and in fear and in much trembling. And my speech and my preaching were not with enticing words of man's wisdom, but in demonstration of the Spirit and of power, that your faith should not stand on the wisdom of man, but on the power of God.
   
However, we speak wisdom among those who are perfect, yet not the wisdom of this world, nor of the princes of this world, who are coming to nought.
   
But we speak the wisdom of God in a mystery, even the hidden wisdom which God ordained before the world for our glory -- wisdom which none of the princes of this world knew; for had they known it, they would not have crucified the Lord of Glory.
   
But as it is written:

"Eye hath not seen, nor ear heard, neither have entered into the heart of man the things which God hath prepared for them that love Him."
   
But God hath revealed them unto us by His Spirit. For the Spirit searcheth all things, yea, the deep things of God.
1 Cor 2:3-10

Apostle Paul wrote those words to the early Christians in the Greek harbour city of Corinth around 50 AD.


He is referring to a much older writing at the end of the Book of Isaiah that scholars often date to 6th century BC Palestine (so called Trito-Isaiah writing after the return from exile in Mesopotamia).


 Oh, that Thou wouldest rend the heavens, that Thou wouldest come down, that the mountains might flow down at Thy presence -- as when the melting fire burneth, the fire causeth the waters to boil-- to make Thy name known to Thine adversaries, that the nations may tremble at Thy presence!
   
When Thou didst fearsome things which we looked not for, Thou camest down, the mountains flowed down at Thy presence.
   
For since the beginning of the world men have not heard nor perceived by the ear, neither hath the eye seen, O God, besides thee, what He hath prepared for him that waiteth for Him.
Isaiah 64:1-4 KV21


Or in the original Hebrew of Isaiah

עליהם לוא־קרעת שׁמים ירדת מפניך הרים נזלו׃
 כקדח אשׁ המסים מים תבעה־אשׁ להודיע שׁמך לצריך מפניך גוים ירגזו׃
 בעשׂותך נוראות לא נקוה ירדת מפניך הרים נזלו׃
 ומעולם לא־שׁמעו לא האזינו עין לא־ראתה אלהים זולתך יעשׂה למחכה־לו׃