First, we must get one thing straight. It is God who works miracles. The Church teaches us that a miracle may happen through the prayers or intercession of a Saint, but God actually works the miracle. So, we should not say I received a miracle from St. Nicholas but, rather, I received a miracle through the intercession of Saint Nicholas.
At the Last Supper, in St. John’s Gospel, Jesus told us to love another. In many other places in the Bible it is clear that we are told to love each other. When we love each other we are concerned about each other. The problem of our friend or relative becomes our problem, in that we want them to have a good life. We do not want them to be sick or have financial difficulties etc. We want them to have a solution to whatever difficulties that they have in life.
Saint Paul tells us many times in the Epistles, to pray for each other. Praying for other people is an act of love. We commit them, and their difficulties, to the love of God, asking God to help them. It shows our concern for other people and that we want them to have a happy life.
If on earth, in a sinful situation, in a very imperfect life, we are called to love each other and pray for each other; how much more should the Saints in heaven be able to love us and pray for us? In heaven they are not tempted to sin and they enjoy closer communion with God. It seems illogical to me to say that the Saints, who are more spiritually advanced than we are, do not love us and are not concerned about us. To say so, would imply that their love has decreased in heaven instead of increased.
Some people think that the Saints would not know what is happening on earth because, to know would make them sad, and there is no sadness in heaven. Here we need to be careful, for sometimes love involves sadness at seeing the misfortune of others. God Himself is saddened by the evil on earth. The joy of heaven does not cancel out the ability to be concerned for others. Love is always at work.