There are many reasons why stained glass works so well in churches and sacred places. But the main reason is that the images on glass have the effect of enclosing the space.
The experience of being in an enclosed space, immediately turns the attention of those inside the space within. It is like closing the eyes, it has the effect of drawing our attention inwards. A sacred space is where we need to listen, where we need to feel and where we need to be still. Glass art, including stained glass, can be a way to create this luminous, but enclosed, space. One which will lift our spirits while at the same time focusing our attention inwards. To create the ideal atmosphere, the glass art should be calming, it should help imbue us with a feeling of peace and, at the same time, of energy, of calm and of resolution.
Stained glass windows can be in the form of a narrative. Ideally, they are in several repeated motifs. These motifs may lead up towards a central point of meditation. In churches you may have several windows that are in a similar format with minor variations. These lead up to the window above the altar, which will be the apex. This might be a crucifixion or similar specific devotional subject. The stained glass windows in the knave creating a calming context, which culminates in a central core theme.
Some spaces, those which are more circular in format, may have no fixed apex, so the surrounding image will sometimes be in the form of woven patterns, with a balance of nature and of stylised patterned forms, all of which combine to create a soothing ambience.
The central theme here is that a visually enclosed space, with light coming in, but the eye unable to wander off into the distance, is the perfect experience for a spiritual experience. We are brought back to ourselves, to our hearts, our thoughts, and our interior experience. Stained glass may be the medium through which we experience the presence of the divine.