I have asked the same question. I have wanted to meet someone today still living who is truely a mystic. So far I have not found any that are still alive. I have met some who knew one that I believe was a mystic. Although the person was not catholic but was a christian who lived in the early 1900s. Her name was Martha Wing Robinson. There is a book that was written about her that contains memours from her diary and various lettars that she wrote during her life. Here is a little of what she wrote. I find it very simular to what the catholic mystics have said. Each seems to say the same thing. Its only that they use differant terms to describe the same thing.
When Jesus first sets vesselsⁿ to love Him, He wants them to see Him all the time, every moment, and if they are very much in earnest, they live that way—moment by moment.
In the beginning of such experience, most of the time they pray, praise, wait on God, commune, and often, if at work, see Jesus in the soul.
If they grow in this experience and become vessels of God for His use, they begin to seek more for Him, and He comes more to them, for He does to all who seek Him from the heart.
Also, He begins to draw their thoughts all the time—every moment—to Himself, causing them to find Him within. This is the beginning of the inward or deeper life.
As soon as this change takes place, He then teaches, if He can make them to get it, either by teachers or by their light, how to “practice the presence of God”—that is, to keep the mind stayed on Jesus—each wandering thought, act, word or feeling being recalled (i.e., called back) by the will of the vessel in the love of God.
However, this takes care. Often the mind lingers over a subject not of God. Turn the mind back to God. Words come not appointed by Him. Check such words at once, as soon as remembered. Look within and tell Jesus He rules, you will act, think, and speak as He would, and He will look after you to help you to be like that.
Also, you need to watch and pray to be in God, wait in God, etc. To so live for a time makes the inward change to abide in anyone who will go down to thus live; but if you keep to this lowliness, rest, and faith to be all the time in God so, then the voluntary act of dwelling in God, seeing God, thinking of God, and keeping in is done altogether by the Holy Ghost, which is the true inwardness called for in every Christian.