The History of Art is full of treasures to be discovered, although they are usually visible to those who contemplate the painting or sculpture in which they are hidden. Manuel Jesús Segado-Uceda offers us in this work some wonderful examples. The reader will feel faced with one of those pastimes that contain errors to be discovered and that are before his eyes, but so well concealed, that he will have to spend more time than he suspected in noticing them. This is the case with many works of art. We contemplate them a thousand times without noticing that they hide information that we did not imagine.