In India, musical modes are called “ragas,” or “states of mind.” A raga can also be defined as a theoretical scale, as a set of proportional  intervals, or as a complex of sounds, each of which has a psychological impact or precise significance. Taken as a whole, they create an emotive atmosphere or state of mind.
Indian psychology envisages nine different sorts of mood or affec­tive states, which are called rasas, “flavors.” They are thus linked to numerical factors, giving us an interesting glimpse into the workings of the brain’s mechanisms and the nature of our aesthetic and emotional reactions. The emotive atmosphere of the ragas is often associated with those that prevail at different times of day and night, or else of the sea­ sons that punctuate the year’s cycle. Like the vegetal world, we react differently in the morning or the evening, in the spring or autumn.
Modal music can only be improvised, since preset forms of melody adversely affect modal consciousness, its internal vision centered on the scale of the mode and the atmosphere it creates. The musician should therefore cruise freely in the inner ambiance created by the mood without ever coming out of it. It is a very intense and a very extraordinary experi­ence, which requires total abstraction from the outer world. In fact, it is a form of meditation that can easily become mystical in character.

The listener is also gradually influenced by the nature of the mode, becoming immersed in a sort of sound bath, which evokes a well-defined feeling. The listener gradually identifies with the emotional scenario evoked. This is why a good performance of modal music can have a profound effect on the audience, making them melancholic, wary, calm, enterprising, aggressive, or tender, according to the atmosphere created by the performer.

In actual fact, any music that seeks to move us – such as what we know as romantic music – requires us to abandon ourselves to the feeling evoked, which takes precedence over technical format. That is why Greek warriors were advised not to listen to certain modes, which stimulate a kind of erotic languor. The Dorian mode was recommended, since it stim­ulates courage and energy. During the Middle Ages, modes deemed to be sensual were forbidden by the church, always sexophobic, not to speak of the augmented fourth, which does in fact open horizons onto the invisible, and was considered to be diabolical, the diabolus in musica.

From Music. The language of the Gods, found in:

Shiva and the Primordial Tradition FROM THE TANTRAS TO THE SCIENCE OF DREAMS  by Alain Danielou (2003.)