Vajrasattva is the visible symbol of cosmic consciousness in its absolute and incorruptible essence. He is the insubstantiality of things itself, the being who is of himself, Sayambhurupa. He is above the five Tathagatas because he is undifferentiated and, in the schools of annuttara yoga, the sixth Buddha, i.e. a moment of being preceding any evolution into the multiple: he is therefore identical with the sarvatathagata-kaya-vak-citta-vajra, the adamantine essence of the physical, verbal and spiritual plane of all the Tathagatas, he who neither beginning nor end. He is always represented with a bell and Vajra. These attributes, essential to every esoteric Buddhist liturgy, are symbols: the first of the emptiness of all things and of the awareness of such emptiness, the second of the meditative process, which translate into psychological experiences and spiritual realization that same awareness. So when Vajrasattva is represented embracing his consort, that same symbolism is expressed by human figures god = vajra, consort = bell that is, the synthesis of the two elements from which supreme enlightenment is derived: gnosis and compassion.
There is legend about the Vajra and bell attribute of Vajrasattva, "In a certain country a lama practiced austerities in solitude for many, many years, and by doing so he attracted the notice of all the inhabitants and even of the king, who, however, hated religion. Once the queen found herself in the pang of delayed parturition and all medical skill proved futile. The king, advised to call upon the saintly lama, sent his ministers to bring him to the court, but the lama refused to obey the royal summons. Even when the king designed to go in person in order to invite him, the hermit did not condescend to accede to his entreaties. Moved however, by the sufferings of the women, he delivered her from the pangs of parturition by his magical powers without even leaving his solitude. The king, anxious to see the holy man at his court, went to invite him once more, with no better result than before. Offended by the lama's stern refusal to go with him, he promised a large reward to any one who could induce the hermit to change his mind. Now a young girl and this is a motif analogous to the famous Ekashringa legend undertook to make an attempt. But although she displayed all her charms, the lama remained as adamant as a Vajra. At last she resorted to crying, telling the lama that she and her whole family would be exterminated if she failed to keep her promise. The lama, pitying her, said with a smile "come". He embraced her and in this posture they remained. A son and a daughter were born to them. Meanwhile the king waited, more and more impatiently, for the arrival of the holy sage. Finally he proceed in person, escorted by his courtiers, to the lonely wilderness, where the couple lived, and seeing what had happened, he sneered at the dissolute lama. But the lama retorted: "Foolish, what do you perceive with your fleshly eyes?" Then he took his two small children and hurled them into the ground. To the amazement of the onlookers the boy was transformed into Vajra the girl into a bell, symbolizing method and wisdom, the way and the goal, which cooperate in inseparable union, like the wings of a flying bird, in order to promote all things on their road to salvation. At last the king realized the meaning that the lama and the girl, yab and yum, Vajra and bell, method and wisdom, are but two different aspects of the same Mysterious."
On the top, Amitabha Buddha is seated, while upper left and right corners have beautifully rendered offering deities in smoky clouds.
A. Getty, The Gods of Northern Buddhism, Tokyo, 1962
B. Bhattacharya, The Indian Buddhist Iconography, Calcutta, 1968
F.D. Lesing, Yung-ho-kung (Quoted in L. Chandra TAT, Delhi, 1996 H.P. Shastri (Ed.), Advayavajrasamgraha, Baroda, 1927
This description is by Dr. Shailendra K. Verma, whose Doctorate thesis is on "Emergence and Evolution of the Buddha Image (From its inception to 8th century A.D.)".