Read the following text, which is an extract from a book titled Paradise Gardens. The Arabian desert is remorseless. Fly over it and the barren vastness is daunting, but to spend your life moving through it on foot, on the edge of survival, is beyond imagination. The only thing that makes life possible, let alone bearable, is an oasis. Without occasional patches of green with fresh water, there would be no life at all. Compared to the intolerable heat, the sandstorms, the interminable salt flats and the razor-sharp rocks, an oasis is heaven on earth. The nomadic desert Arabs lived in the harshest and least fertile of environments that could support any kind of human life. By the early seventh century AD, a garden was something they arrived at as more than just a relief from the rigours of the desert; it was a symbol of life underlined by the one great essential – water. It is a common cliché to refer to your garden as 'a little bit of heaven' or as 'paradise'. This is shorthand for saying that it seems just about perfect, combining beauty and peace and – momentarily at least – it is devoid of all care. But for the desert Arabs of the sixth and seventh centuries, an oasis really was paradise and paradise was inevitably going to be just like the perfect oasis, running with water, full of fruits and green with luxuriant shade. The Qur'an made all this explicit. There are over 120 references to the gardens of paradise, and the phrase most often mentioned is 'gardens underneath which rivers flow'. Water in physical form flowing through and beneath gardens and flowing within this beautiful, abundant peaceful place is the heart and essence of the paradise garden. The concept of paradise being a garden goes back almost five thousand years to Babylon, but the first reference to the word comes from the Persian 'pairidaeza' which means an enclosed garden filled with trees – and especially fruit trees. This pre-dates the Islamic idea of a paradise garden by at least a thousand years. By 530 BC Cyrus the Great had made a large garden at his palace at Pasargadae complete with sophisticated water channels and pools. When the Arabs conquered Persia in AD 650 they took on the idea of the four-part chahar bagh. This became the model for paradise gardens throughout the Islamic world thereafter, albeit with many variations. The four rivers, of milk, honey, water and wine, flow from its centre. Four is a magic and holy number and the cube the perfect shape, so four features in every paradise garden and the number eight, derived from it, are very common. The central fountain with flowing water is also essential. Moving water is the key for many reasons. The movement symbolises life, but it has great practical implications too. Water cools and dampens the air, it produces a musical sound that is conducive to contemplation and peace and it can be used for irrigation. All fruits were grown – often in deeply sunken beds so the tops of the trees were at head height for those standing on the paths dividing the charhar bagh – although rarely in mixed orchards. Olive and fig, date and pomegranate were ubiquitous and symbolically important. The orange arrived from India via the Silk Road by the eleventh century, and was planted throughout gardens primarily for the fragrance and beauty of its flowers and fruit but also as a bitter oil in cooking; the sweet orange came much later. Flowers would be grown beneath the fruit trees but not in borders as such. In any event, flowering was largely restricted to a brief spring explosion before the searing heat kicked in. It is hard for northern Europeans to imagine the extreme summer heat of the desert or places such as northern India where the temperatures can rise above 50 degrees. Shade, coolness and green repose become the greatest luxuries. Fragrance, gentle sound, good company, beautiful carpets and silks and delicious fruits are a sensual refinement. Add to all this the senses of safety and harmony that come within the protective confines of a domestic garden, and you have a good measure of paradise – and the knowledge that this is just a cloudy reflection of true paradise, merely an inkling of the heaven that awaits.