Generally speaking, a miracle is an event attributed to some kind of supernatural intervention; there is an interruption to the laws of nature or just simply something that is unlikely to happen yet beneficial and even wonderful.
So it can be said that a miracle usually brings about something good, such as escaping danger and injuries, surviving from a certain deadly situation, or just beating the odds.
We don't usually say that what happened to Zacchaeus, that wealthy senior tax-collector in today's gospel, is a miracle.
We may simply call it a conversion and repentance. But the effect of Jesus calling out to Zacchaeus was simply amazing, if not miraculous.
The man changed immediately and became a generous, open-handed and charitable benefactor.
Jesus called out to him in love while he was on that sycamore tree and he listened and responded.
If anything, we can say that the miracle was that Zacchaeus listened and responded to Jesus.
Yet in the 1st reading, it seems that the Lord Jesus is pleading with the churches in Sardis and Laodicea to listen to Him and He said this: If anyone has ears to hear, let him listen to what the Spirit is saying to the churches.
But what is said to the churches is also said to us and it is up to us to listen and respond to the call of conversion and repentance.
What happened to Zacchaeus was indeed a miracle. And miracles will happen to us too - when we listen and respond.