The Sight is the ability to see past glamour to a thing's true nature.
Most Shadowhunters are born with the Sight, inherited from their Shadowhunter parents. The Voyance rune, the most basic and permanent Shadowhunter Mark, serves to focus and enhance their Sight. It is applied on essentially all Nephilim, typically on the back of the right hand. With training and practice, this will help Shadowhunters identify Downworlders on sight. It is assumed that Raziel granted the Nephilim the power of glamours and the Sight.
Gaining the Sight and being able to see through glamours can be learned through training. Usually, new adult Shadowhunters first receive a Voyance Mark. They also receive other temporary Marks that enhance magical vision, but is ultimately not kept because they impair normal vision in the long term. Despite this, Shadowhunters still have to concentrate for harder glamours.
While most Shadowhunters have the Sight from birth, or gain it in the first two or three years of their life, some are born "blind" and must be trained to see. Usually, it is sufficient to deliberately show children glamours and their revealed true shapes; this produces full Sight in almost all Shadowhunter children by the time they are beginning their training in earnest, at five or six years of age; however, as they grow older, they need the further assistance of Marks to develop the skill.
Before it was made illegal, it was traditional in some parts of the world to "jump start" a Nephilim child's Sight by inscribing a deliberately weak Voyance Mark on the child, while purposefully wounding the skin under it to disrupt its effectiveness, at a much younger age than is considered safe. When the Marking was successful, some haphazard level of Sight occurred at times for the child, and at least sometimes this successfully caused the child to have the Sight permanently even after the Mark was removed. Unfortunately, this process also occasionally caused children to die of shock, from the simultaneous effect of a too-early Mark and the abrupt appearance of Sight. The practice is still done in a few places, but has mostly disappeared in the modern age.
Mundanes who naturally possess true Sight, or are born with it, are usually credited as having fey blood in their ancestry, though no direct connection has ever been proved. Not only can they see through glamours, but they also know certain things, and are said to have the ability to see into the future.
Mundanes whose families have, somewhere in their history, faerie, werewolf, or Nephilim blood that persists through generations are often identified as having the Sight, able to see through some glamours. Most, however, still never notice any supernatural activity, because they are not prepared to see it. An important rule of glamours is that, for the most part, people see what they wish to see; even Sighted mundanes will often look past strange appearances and explain them as illusions or misunderstandings.
Many of these mundane-yet-Sighted families used to act as the servants and caretakers of various Institutes and wealthy Shadowhunter families. Those employed at Institutes are also trained to fight like Shadowhunters to be able to protect themselves. However, in most parts of the world, the practice of keeping servants has long gone out of fashion, and these families have ceased their relationships with the Nephilim. Several generations have passed since this happened in North America and Europe, and most living members of these families no longer even know that their ancestors once served the Nephilim.
While most Shadowhunters and Downworlders possess the Sight, it is rarer among mundanes. Mundanes who are known to possess the Sight include:
- Sophie Collins - former London Institute maid and later Shadowhunter
- Thomas Tanner † - London Institute carriage driver
- Cyril Tanner - London Institute carriage driver
- Agatha Grant † - London Institute cook
- Bridget Daly - London Institute cook
- The Sight also grants those who possess it the ability to see ghosts.