Steinbeck's worldview was one of a fatalist, and the novel Of Mice and Men shows an insightful but tragic view of the world as it was in that era. The farm was a dream; it helped to calm and control Lennie, it made the days worth living, and it provided hope to all of those involved. I believe that George knew that dream would never come true, but that even for him it had a purpose.
The worldview of the depression era was one of hopelessness, and there was little help to be had for the conditions of man in the United States at that time, especially for those like Lennie who were unable to help themselves. Choices had to be made, but they were choices without options. It was George's dream to take care of Lenny, without him it would have been an institution. Lenny was enslaved by his handicap;l George was enslaved by a promise, and the farm in its own way would have freed them both.