Do we understand crystal clear thinking? Perhaps, when someone is expressing clear thoughts we understand the concept, but in reality, we really do not understand what happens inside the brain when one is thinking clearly. But now in a Nature paper, scientists at Stanford University have unveiled CLARITY, which is an acronym for a technique to render a post-mortem brain completely clear, that is, optically transparent and permeable to macromolecules. One day CLARITY may help us understand clear thinking and much more. Importantly, it could give us a handle to better understand the extremely complex neuronal circuitry in the brain, with its 1014-1015 synapses. It could help us better understand the abnormal circuit wiring that occurs in humans affected by developmental pathologies, such as many psychiatric disorders. What an exciting moment for us to be witnessing this discovery!