It is not too hard to imagine what the Savior may have been thinking about in his sorrow. As the multitude knelt down, perhaps the Savior had time to think about how small the group was. He who would have gathered them as a hen gathereth her chickens must have grieved at how many of that generation had been lost. Alternatively, he may have seen the wickedness which was to come. He later mourned, behold, it sorroweth me because of the fourth generation form this generation, for they are led away captive by him even as was the son of perdition (3 Nephi 27:32).