Puja

To give birth to a god requires a considerable act of imagination. It's too big a job for most of us to pull off on a first attempt. Knowing this, the ancient sages have passed down to us the technique of Puja, whereby one can build up the image of the deity bit by bit. Each bit is a symbol or set of symbols which describe the deity in a particular way. Every symbol begins at a different point within the mind, and grows larger the more you meditate on it. Eventually the symbols start to link up with each other, describing the same aspect of the deity in different ways. When this begins to happen, the process unconsciously continues 24 hours a day (perhaps more) until the image of the deity becomes coherent (although it may still be impossible to call that deity into consciousness). Once such an image has been formed, it becomes inhabited by the god or goddess in question, and one can work magick with the her or him. Puja is therefore a very useful mystical and magickal practice which opens the door to a multitude of fascinating new experiences.

http://www.cix.co.uk/~ganesh/ganesha4.htm