Why didn't Major begin his speech by describing his dream?
Major doesn't begin his speech in this way because he wants to lead up to the dream. He wants to make the animals intrigued and curious to hear what the dream is. Also, for the dream to have more impact, he wishes to impress the animals first of all by commenting on how badly off they are at present, and then contrasting this grim sordid picture of life as it is with a glowing picture of life as it could be, as described in the old song, 'Beasts of England' which came back to him in his dream. Major is the great visionary who wishes to pass on his ideals to the rest of the farm animals before he dies.