Before God grants a grace He grants a hunger for it as a preparation. In the Early Persecution of the Church in Ancient Rome, Catholics generally had a huge hunger for martyrdom. A hunger which God granted in full.
I was just thinking last night coming from Mass about the Dark Night and it brings back many, many memories. One think I would say in general is that like any other deep topic the more we read about it the more we come to understand it. A little knowledge can be a dangerous thing. A little knowledge can be a dangerous thing. We may, for instance read one book and kinda think we understand. But there is a huge, huge amount written including by saints, mystics, poets and mystical theologians and the more we read the better if we seek understanding. In addition to this we can't beat experience and having gone through it ourselves just can;t be beaten for understanding. The danger is we might have a one fit understanding that leads us to think the Dark Night has to exactly the same for everyone it does not. One example id the time it lasts from person to person. For myself it lasted for around 24 years. For others just a few brief years, for others far less. The intensity of the experience will also vary greatly from person to person and even how they describe it. Another thing is the onset of the Dark Night,at which point in the Spiritual Life it happens. Generally it is taken as a preparation for the last stage of prayer, Mystical Marriage but this is not always so. Another thing is that there are two kinds of Dark Night . That which is Salvific and that which is Redemptive. The Dark night of inner purification to get out own pot scrubbed clean and suffering to save others. You can look at it as a chalice , it gets filled with wine and then it overflows to help others. So a Dark Night for your self then a Dark Night for others.
Another thing is that the Dark Night is that it comes to people of all ages and conditions and will be coloured by this. St Teresa of the Andes was a good example of this. She had just entered Carmel after leaving school but her Prioress considered she had already passed through the Dark Night and was in the Highest stage of prayer. Her novice mistress considered this incredible. But Teresa was to die very young and so God worked quicker, so to speak. God is Master in His own House and can do as He pleases, people forget this.