This book is found in The Calmecac.
Roughly equivalent version of the Mist in Camp Half-Blood series, the Veil is the supernatural force that existed since the dawn of chaos. The Veil removes or censors a mortal's vision from seeing gods, monsters or supernatural occurrences by replacing them with what the mortals could think of or removing it from sight completely.
The Veil was formed after chaos settled during the Creation of the Earth. The gods themselves were unable to remove this barrier that removes the mortals they had created from seeing the gods but allowing them to intervene in events freely. Demigods and mythical creatures can all see through the Veil at most times (though sometimes the Veil is strong enough to fool demigods). The Veil's power is known to be strong but its full power is yet unknown. It has been shown to remove memories and create a solidified barrier.
Many people are able to control the Veil lessening it or increasing it. The technique itself was given to the demigods by gods. Some people if they had trained enough could bend the Veil into turning them completely invisible to mortals. Unfortunately, it does not allow demigods to be invisible to gods and monsters.
The Veil's thickness varies across the globe. Places such as Manhattan, San Francisco, Tokyo, places around Madrid and Barcelona, Port-au-Prince, Lima and areas on Yucatan Peninsula have high Veil thickness. Weak Veil thickness are Mexican ruins of Toltec, Olmec and Mexica peoples. These places make demigods prone to attack more. Veil of Sight barely exists in the Northernmost regions of the World
The Veil has its disadvantages however. The Veil is somehow useless to remove written words but enough to distort them. It is hypothesized that the Veil's inability was due to being written in English not Nahuatl. If many knew of the existence of the Aztec gods in the certain area, the power of it began to weaken until it ultimately disappeared. The City and Camp is surrounded by the Veil but does not envelop all things in it.
Clear-sighted mortals are mortals that could see through the Veil's powers. This is probably due to their ancestors being divine or semi-divine (though demigods' descendants loses their powers quickly unlike fully fledged demigods) or the fact that they made deals with gods. In the Aztec Empire, these people were known to be officials of the cities. There are a very few clear-sighted people currently on the globe.
The Veil as a mode of communicationEdit
Most people have claimed to have the ability to use the Veil as messages. This is currently unknown as so we'll just go with mobile communication instead.