Does 1 Corinthians 2:9 mean Heaven will be more joyous than we can contemplate?

This is one of those passages that is more metaphorical and should be taken in context with the entire passage, and, like the entire New Testament, it should be taken in context with common Judaic beliefs of the day.

The people to whom Paul is speaking know what heaven is supposed to be like. The resurrection of the dead and the paradise that awaits is often repeated. Paul wouldn't be trying to describe heaven in a single verse to people who'd been hearing about heaven their entire lives. Verse 9 is an analogy used to explain that Paul didn't come up with this stuff on his own. He is teaching what God taught him.

Simply, Paul is saying that compared to anything any person could have come up with, this wisdom from God is like this world compared to what we know heaven will be like.

Let us consider the passage in context.

1 Corinthians 2:6-13 (NASB) 6 Yet we do speak wisdom among those who are mature; a wisdom, however, not of this age nor of the rulers of this age, who are passing away; 7 but we speak God’s wisdom in a mystery, the hidden wisdom which God predestined before the ages to our glory; 8 the wisdom which none of the rulers of this age has understood; for if they had understood it they would not have crucified the Lord of glory; 9 but just as it is written,

“Things which eye has not seen and ear has not heard,
And which have not entered the heart of man,
All that God has prepared for those who love Him.”

10 For to us God revealed them through the Spirit; for the Spirit searches all things, even the depths of God. 11 For who among men knows the thoughts of a man except the spirit of the man which is in him? Even so the thoughts of God no one knows except the Spirit of God. 12 Now we have received, not the spirit of the world, but the Spirit who is from God, so that we may know the things freely given to us by God, 13 which things we also speak, not in words taught by human wisdom, but in those taught by the Spirit, combining spiritual thoughts with spiritual words.

Take note of instances of the phrase "it is written" in Pual's letters. This usually means that he is about to quote from the Old Testament. Some modern bible translations typeset such passages in all capital letters. In these cases, check your Bible margins or do an internet text search for cross-references. In this case, Paul is paraphrasing Isaiah 64:4:

Isaiah 64:4 (NASB) For from days of old they have not heard or perceived by ear,
Nor has the eye seen a God besides You,
Who acts in behalf of the one who waits for Him.

Given the circumstances, this answerer's opinion is that Paul's translation is probably better.

So, why is Paul quoting from Isaiah?

In the context of the passage you cited, we see that Paul is criticizing the contemporary religious leaders of the Jewish people for being stiff-necked and presumptuous.

Notice that Paul is talking about a hidden wisdom that God predestined before the ages, and he says of this hidden and ancient wisdom that if any of the rulers of this age has understood it, they would not have crucified Jesus Messiah.

Paul is bringing to the attention of his readers that the Hebrew leaders, despite their boasts of both righteousness and understanding, completely missed God's plan for them, not only when it was revealed in the Prophets, but even when it was revealed before their eyes.

What is the Hidden Wisdom?

Paul continues to say that believers have received the Spirit who is from God so that they may know the things freely given to us by God, which things Paul and the Apostles also speak, that is The Gospel of Jesus Christ. If the ruler's of that day had understood the message that the Spirit revealed to the Prophets, then they would not have crucified the Messiah.

However, Paul makes it clear that this hidden wisdom is not

How did Paul and the Apostles know, when the religious leaders did not?

Paul makes it clear after citing the prophet that this hidden wisdom is known and revealed by the Spirit. He says, "For to us [the Apostles and churches] God revealed them through the Spirit; for the Spirit searches all things, even the depths of God.

He includes the clause "even the depths of God" to contrast believers with those that he was criticizing and to set them apart from those who cannot know what God has prepared for them: Messiah. Paul says that we have the Spirit so that we may "know the things freely given to us by God", and Paul boldly continues, "For who has known the mind of the Lord, that he will instruct Him? But we have the mind of Christ."

For this reason, I would answer difinitively that no, this passage is not saying that we cannot contemplate the joy of Heaven. In fact, it's quite the opposite: because we have the Spirit, we can contemplate that joy.