Sometimes you can only catch on too late that you missed a wonderful opportunity that can never be recaptured...
The Temple had been rebuilt in Jerusalem, but those who had seen the previous one that Solomon had built wept at how poor the new one looked in comparison (Ezra 3 v 12). Haggai had a message for them which was that the glory of this new temple would actually exceed the glory of Solomon's (Haggai 2 v 7-9) and would be filled with glory! The people might have wondered what Haggai was talking about, and they might have continued to wonder about it until the temple was tumbled in 70 AD. In what sense did its glory surpass the majesty of Solomon's temple - it wasn't by the additional adornments Herod provided. It could only be because God had actually visited the temple in the Person of the Son - the Messiah who was promised, the Saviour who was needed - the Lord had come, and the majority had missed it (John 1 v 10-12). Daniel had prophesied that prior to the destruction of the temple the Messiah would die (Daniel 9 v 26). After the destruction of the temple you can reject any further applications for Messiahship! So the sad thing is, those who are expecting the Messiah to come the first time have missed Him - He's already been here. If it's not Jesus of Nazareth then who is it? He's the only one who fits the description and fulfilled the required mission in the given timescale.
The Lord Jesus said to some men that they would realise too late that He was the One they needed (John 7 v 34). I'm glad that there's still opportunity for you today to come to the Saviour. Many missed their opportunity when He was here; many are in danger of missing their opportunity today. I would urge you to come to Him now and receive the mercy and salvation that He alone can give. The regret of missed opportunities will be one of the most heavy burdens and intense agonies for the soul in hell to bear.
