“Meditation can be defined as a state of consciousness characterized by stillness and inner calm. The ultimate goal is the attainment of supreme spiritual peace. Meditation takes you beyond the restless activity of the mind to a deeper, more peaceful space.
Meditation is mental maintenance. The mind needs to be stilled occasionally to keep it working at peak efficiency. Teaching yourself how to relax your mind and release it from the stress of thought for a short period each day keeps it clear and clean. You’ll think better. You’ll see more accurately and with more insight. You’ll be able to concentrate and focus on things like never before. You’ll be able to truly relax.
Meditation differs from deep sleep or relaxation in that it involves active mental effort rather than total rest. As well as relieving stress and replenishing energy, it can bring you physical, mental, and spiritual peace. You will develop awareness – the capacity to notice fully every event in your life as it happens.”
Edith Howell has written more on the subject here – http://www.yogaforbeginners.com/meditation01.htm