What desirest thou? is the question Nephi is asked by the Angel when he is taken away to a high mountain in response to his desire to understand the vision of the Tree of Life that his father Lehi had seen. (1 Nephi 11)
I have been pondering this question in my own life and wondering if I was asked the same question what would my answer be? What do I desire? Like Nephi do I desire to understand more fully and more personally the words of the prophets? Like Nephi do I put forth the effort to inquire of the Lord (1 Nephi 15:8)? or like Lamen and Lemuel do I think the things that the prophets ask are Hard (1 Nephi 16:1)?
And in a broader sense what if the real test of this life is that question. What desirest thou? What if that is the true test of our discipleship and probation is the answer to that question?
Our desires are an important test of our heart and the dedication or lack there of to the Lord.
Alma discusses the importance of desire at the judgement bar here:
This desire is certainly one that would help you gain mastery of your other desires?