This technique is often helpful after a period of fasting from impressions. Another means of controlling the senses is to create positive, natural impressions. Positive impressions can also be created by using incense, flowers, ghee lamps, altars, statues, and other artifacts of devotional worship. Another sensory withdrawal technique is to focus the mind on inner impressions, thus removing attention from external impressions. We can create our own inner impressions through the imagination or we can contact the subtle senses that come into play when the physical senses are quiet.
Visualization is the simplest means of creating inner impressions.
More elaborate visualizations involve imagining deities and their worlds, or mentally performing rituals, such as offering imaginary flowers or gems to imagined deities. The artist absorbed in an inner landscape or the musician creating music are also performing inner visualizations. These are all forms of pratyahara because they clear the mental field of external impressions and create a positive inner impression to serve as the foundation of meditation. Preliminary visualizations are helpful for most forms of meditation and can be integrated into other spiritual practices as well. Laya Yoga is the yoga of the inner sound and light current, in which we focus on subtle senses to withdraw us from the gross senses.