Glass is a liquid. Even the glass in your window panes is moving – infinitely slowly, but moving all the same . Heat glass up till it is red gold and glowing, and the liquid will flow. Shape it, and when it cools and settles it will remain in that shape; but always, it remains a liquid in perpetual slow motion.
The core challenge of glassblowing is that the artist has to work with the heated medium as a moving, flowing liquid. They have a limited time to work and shape it whilst it remains hot enough, yet at the same time this liquid must be kept in constant motion to make sure it does not flow or fall.
With these constraints, glass blowing becomes not only a craft, but an amazing visual experience. It becomes a dance as the molten glass is kept perpetually moving, twirling, twisting and spinning, whilst all the while the glassblower works on the creation, shaping, colouring and cutting the bubble of glowing liquid as the piece comes into being.