Hi, Jim —

St. Jude is traditionally seen as the patron of (otherwise) hopeless cases; St. Peregrine is the patron saint of cancer victims.

The Catholic Church sees herself as a family rather than simply an individualistic venture before God. When Catholics pray to saints they pray for their intercession. In other words, they ask for their help before the Throne of God, who possesses all power. In the same way you might ask me to pray for your mom, for example, you would also ask a saint. The difference is that their prayers to God are more powerful than mine, seeing that I am a sinner still on my earthly journey and they are in complete union with God in Heaven.

When it comes to patron saints, some who had similar situations or circumstances when they were on Earth, or who were given certain gifts by God and developed them, have been labeled the patron saint of (a problem|a gift| or, of people). It is an honor for them who now want to intercede for us from Heaven. They are our older brothers and sisters in Christ, who have crossed the finish line before we did. We can rely on their assistance before God, who allows this family intercessory dynamic to occur. We can pray directly to God, as we should. It's not necessarily an (either|or) way of thinking but an (and|both) way. There is a phrase in the Divine Praises prayer that states:

Blessed be God in His angels and in His saints.

To answer your question directly, the saint does perform the miracle, but only by being given a share in God's power and only by God's permission.

Peace,

Paul