All so called Christian art is Biblically based; and is intended to induce some reflection of some event in Biblical History otherwise it would not be Christian art. Even going back to the old Masters, much or even most of their artworks were based on their concept of some event from the Bible.
The picture you asked about along with many other paintings are symbolic and are intended to elicit contemplation on the part of the viewer. As to what that painting refers to in the Bible is mostly an association within the mind of the viewer.
One person might be reminded of the temptation of Christ when Satan said turn these rocks into bread while another person might be reminded of the aloneness of Jesus and that he was like no other man who ever walked the earth. The more connotations that a painting can induce in it's viewers the better.
The painting itself readily identifies itself with Jesus in it's title and for my part it represents many facets of Jesus life on earth. His loneliness, his deep concentration, among many others.
And although it most likely will be deemed off topic I felt it necessary to give you this explanation even though I will be called down for answering an off topic question.