Kundalini.

Kundalini.
“Without Shakti, Shiva too is a corpse.” Shakti ke bina shiva bhi shav hai.
The realization of Shakti in one form or the other has been known since times immemorial. Poet writer Bana, who wrote his Hundred Couplets to Chandi, Chandi-shataka and Bhavabhuti his play Malati Madhava, both of which praise the height of Shakti.
Shakti is an amalgam of Shaivism and folk mother-goddess cults. The Shaiva cult that not Shiva himself but his shakti sexual, creative power is active is taken to the extreme, that, without Shakti, Shiva is a corpse, and simultaneously that Shakti is the creator as well as creation.
Kundalini is described as a sleeping, dormant potential force in the human organism.
It is one of the components of an esoteric description of man's 'subtle body', which consists of nadis energy channels, chakras, psychic centres, prana, subtle energy, and bindu, drops of nector.
Kundalini is described as being coiled up at the base of the spine, usually within muladhara chakra. The image given is that of a serpent coiled 3 and a half times around a smoky grey lingam. Each coil is said to represent one of the 3 gunas, with the half coil signifying transcendence.
Through meditation, and various esoteric practices, such as kundalini yoga, laya-yoga, and kriya yoga, the kundalini is awakened, and can rise up through the central nadi, sushumna, that rises up inside or alongside the spine. The progress of kundalini through the different chakras leads to different levels of awakening and mystical experience, until the kundalini finally reaches the top of the head, Sahashra chakra, producing an extremely profound mystical experience.

In yoga, great importance is ascribed to mantras, which conjure up the realities with which they are identified. Another important ingredient derived from yoga philosophy is that through the body run subtle canals that carry esoteric powers connected with the spinal cord, at the bottom of which Shakti is coiled around the lingam as Kundalini, she can be made to rise through the body to the top, whereupon release from samsara takes place.
There are two nerve currents in the spinal column, Pingala and Ida, and a hollow canal Sushumna running through the spinal cord. At the lower end of the hollow canal is the "Lotus of the Kundalini".
They describe it as triangular in form in which, there is a power of the Kundalini, coiled up. When that Kundalini awakes, it tries to force a passage through this hollow canal, and as it rises step by step, as it were, layer after layer of the mind becomes open and all the different visions and wonderful powers come to the Yogi. When it reaches the brain, the Yogi is perfectly detached from the body and mind; the soul finds itself free. We know that the spinal cord is composed in a peculiar manner. If we take the figure eight horizontally, there are two parts which are connected in the middle. Suppose you add eight after eight, piled one on top of the other, that will represent the spinal cord. The left is the Ida, the right Pingala, and that hollow canal which runs through the center of the spinal cord is the Sushumna. Where the spinal cord ends in some of the fine fibre issues downwards, and the canal runs up even within that fibre, only much finer. The canal is closed at the lower end, which is situated near what is called the sacral plexus, which, according to modern physiology, is triangular in form. The different plexuses that have their centers in the spinal canal can very well stand for the different "lotus" of the Yogi

Important among the Shakta Tantras are the Kularnava Tantra Ocean of Tantrism, which gives details on the "left-handed" cult forms of ritual copulation, the Kulachudamani, Crown Jewel of Tantrism, which embroiders on ritual; and the Sharada-tilaka Beauty Mark of the Goddess Sharada of Laksmanadeshika, 11th century, which discusses magic.
A temple was erected in honour of the mother goddess Shakti at Gangdhar, Rajasthan, in AD 423. There, magical rites of a terrifying kind were practiced, for the temple is described as "loud with the shouts of demons, crying in the thick darkness, by the playwright Bhavabhuti, about the adventures of the hero Madhava and his beloved Malati contains a scene depicting secret rites with human sacrifice and ritual cannibalism. The goddess cults eventually centered around devi Durga, the consort of Shiva, in her fiercer aspect.

The play is set in the city of Padmavati. The king desires that his minister's daughter Malati marry a youth called Nandana.
Malati is in love with Madhava ever since she saw him and drew his portrait. Madhava reciprocates, and draws a portrait of her in turn. Malati suspects her father's motives also tied with the King's plans for her. A side plot involves the lovers' friends Makaranda and Madayantika. The latter is attacked by a tiger, and Makaranda rescues her, getting wounded in the process. After numerous travails, all ends well, with the two couples uniting.