deceptive sources

I thought it was interesting that letters during this time period were not dictated but reconstructed by the sender, directly. It seems to me that these would be very unreliable sources. However, letters are used extensively in this book as primary sources. By his own admission, Mieroop is deconstructing his own argument. Also, the author talks about the letters sent to officials by Hammurabi, which weren't actually written in his words. Mieroop says of these, "Thus they are not very informative in this respect." The fact that no real letters have been found to tell about Hammurabi's personality could be indicative of his being illiterate. But, at the same time, it concerns me about the validity of Mieroop's reconstruction of Hammurabi himself. Is it better to guess about the nature of an important historical figure from less than reliable sources, or to just accept what you do not know? In this situation, I think it is better to accept that the past sometimes just stays buried.