<p class="western" style="margin-bottom: 0in; line-height: 100%;"><span style="font-family: Verdana,sans-serif;"><span style="text-decoration: none;">Coherence is a measure of how much our beliefs hang together. Understanding is achieved when we see that something is not just a brute, isolated fact. This suggests that it might be possible to develop a coherence theory of understanding, which is what we attempt to do in this article using several formal measures of coherence. However, it turns out that a coherence theory runs into trouble with the asymmetry of understanding. We identify four difficulties and give suggestions for how they could be solved. These solutions all point away from coherence and towards a rather different notion, uni...