Thanks for the encouragement. Last night for the first time I heard him growl. I believe he was growling at a perceived danger outside, but I looked at him sternly and said "don't you be growling at me" -- then he curled up on the floor. He'd just been out in the yard and had been barking . . . I think he thought he was warning me of something.
Also I'm teaching him to sit -- every time we go outside or before I feed him, I make him sit. As well behaved as he is, I'm surprised he didn't already know this. When we go for walks, he's very good about staying right beside me. He is mildly curious about other dogs. He doesn't cower or puff up either when a dog is barking at him -- he just looks at them as if to say, don't worry little fella, I'm not going to hurt you.
A little schnauzer took a great interest in him and was jumping all around (behind a fence). Einstein just stood there very patiently and let the little guy sniff him. He truly is a gently giant.
One more thing -- he was very obliging and let me brush him -- most of him. He's going to have a bath this weekend and I'm hoping he is agreeable about it. Does anyone have any advice about what to do to help his coat grow in thicker? When he was turned into the shelter he had patches of missing fur on his sides and his elbows. I don't think the elbows will be growing back in, but his sides seems to be filling in pretty well. He's also a little thin on his snout.
Thanks for your feedback and I'm so happy to have this forum.