The intellectual vocation is like every other: it is written in our instincts, in our powers, in a sort of inner impulse of which reason must judge. Our dispositions are like the chemical properties which determine for every body, the combinations into which that body can enter. A vocation is not something that can be had for the asking. It comes from heaven and from our first nature. The whole point is to be docile to God and to oneself as soon as they have spoken.
Understood in this sense, Disraeli's saying that you may do what you please, provided it really pleases you, contains a great meaning. Our liking, if coordinated with our fundamental tendencies and to our aptitudes, is an excellent judge. If St. Thomas could say that pleasure characterizes functions and may serve to classify men, he must be led to conclude that pleasure can also reveal our vocation. Only we must search down into the depths where liking and the spontaneous impulse are linked up with the gifts of God and His providence. (pp. 4-5)
This is the way I discovered I was not to be a linguist. I had ( and continue to have) a deep love of languages, but not the aptitude for them. Specifically, I have no memory for vocabulary, so I will forever be reliant on the dictionary for words that I have looked up over and over again. A true linguist, such as my son, cannot have this defect. A linguist who had worked as much with Latin and German as I have would be fluent in the languages by now. I'm not. So, I get to be a theologian. I seem to be able to do that kind of work.
Oh, thanks to Jeff Vehige for directing me to this work.