I didn't read it all but I think the purport of the letter was that he will not be returning for at least a year.我没有把信读完，但我想这封信的大意是说他至少一年不回来。The gist of the article is that children should have more rights in deciding their own futures.文章的大意是说孩子应有更大的权利决定自己的未来。The drift of his letter is that he wants to come back.他来信的大意是说他想回来。