What is the purpose of reciting mantras?
Mantras are prescribed syllables to protect the mind. What we want to protect our mind from are attachment, anger, ignorance, and so on. When combined with the four opponent powers, mantra recitation is very powerful in purifying negative karmic imprints on our mindstream. While we recite mantras, we should also be thinking and visualizing in a beneficial way so that we are building up constructive habits in the mind.
In the Vajrayana practice, mantras are recited in Sanskrit, rather than being translated into other languages. The reason for this is that there is a special beneficial energy or vibration that is induced by the sound of the syllables. While doing recitation, we can concentrate on the sound of the mantra, on its meaning, or on the accompanying visualizations that the master has taught.What does the imagery in tantric art mean?
Vajrayana deals a lot with transformation, and therefore, symbolism is widely used. There are representations of some deities, which are manifestations of the Buddha, that are expressing desire or wrath.
The sexual imagery is not to be taken literally, according to worldly appearances. In Vajrayana, deities in sexual union represent the union of method and wisdom, the two aspects of the path that need to be developed in order to attain enlightenment.
Wrathful deities are not monsters threatening us. Their wrath is directed toward ignorance and selfishness, which are our real enemies. This imagery, when properly understood, shows how desire and anger can be transformed and thereby subdued. It has deep meaning, far beyond ordinary lust and anger. We should not misinterpret it.http://www.fpmt.org/faq/buddhism_faq.asp#bteach