Water

The poet Philip Larkin wrote that he would have used water if called in to 'construct a religion', conveniently forgetting that all the main religions already make use of this essential substance in deeply symbolic ways.
In exterior design water has always played a pivotal role - indeed the very first gardens were devised as ways of providing access to water and the shade of trees thus enabled to grow in otherwise hostile desert environments. In these settings too, water played a symbolic role. Water can soothe, excite, reflect the changing sky, provide focal points and demarcate pathways and routes of flow. In the grandest gardens it has often been used to define a dominant axis. It can be still, offering a chance for contemplation and allowing the eye to rest after the stimulation of a crowded and visually busy part of a garden, or it can move, making noises from the gentlest murmur to a galloping roar - although the gardens where this is possible are necessarily on the largest scale. In the history of landscape design it has been poured, sprayed, sprinkled, dripped, channelled, dammed and, just occasionally, left to its own devices.
In my own small garden I am having a large, free-standing tank constructed. This will be the dominant feature in the garden, and it will have water plants, fish (if the cats keep their paws to themselves) and in a few short weeks an ecology of its own. I can't wait for my first dragonfly - I'm banking on May next year. It will also, as in the photograph above, bring the sky down to ground level, reflecting light.