Magic has been performed by illusionists for almost as long as history has been recorded. Records dating back more than 4,000 years to ancient Egypt show illusions were performed for ancient pharaohs. Many of the basics of magic were reached in Europe in the Middle Ages. However, medieval magicians were often accused of witchcraft. Magicians often work with a team of assistants who help them complete complicated tricks, such as the hand through glass card trick.
Magic as performed in the modern world is the completion of a series of illusions performed by misdirecting the people watching the trick. Magicians don't practice real magic and instead simply deceive the person taking part in the trick. It is important to remember when watching a performer that they have no specific magical abilities and the secrets to completing most tricks can be found with a quick search of the Internet.
There are three main secrets to completing the hand through glass trick, which are a fake piece of glass, a willing accomplice and the ability to direct the attention of any viewers away from the glass. A piece of glass matching the window or aquarium to be used for the trick has a small hole cut in it that the magician can place his hand through. The piece of glass should be sitover an existing pane of glass to deceive the viewer.
The magician asks a person they have apparently never met to choose a card from a deck and sign the face of it. The card is then returned to the deck by the magician, but as the magician makes conversation with the volunteer, the signed card is discreetly passed to his assistant. This assistant places the signed card behind the pane of glass with the hole, which is then lifted into place in front of an existing pane of glass.
As the magician's assistant is placing the fake pane of glass into place the magician converses with any viewers and uses showmanship to distract their attention from the glass. Once the fake glass is in place, the magician, showing great force, pushes a hand through the hole. Removing the hand with the card, the magician again moves with great exaggeration to distract the viewers as the fake pane of glass is discreetly removed.