Also called " buddhas of the forgiveness of sins”, they all have the essential characteristics of a buddha but vary as to colour, mudras and hand objects. The 35 Buddhas were invoked once a month in the rite of aptittadesanavidhi (Tib. lTung-ba bshags-pa´i cho-ga ), when all the monks of a monastery solemnly made a collective confession of guilt. The thirty-five buddhas are seen as counterparts to the main crimes of human thought and action. Their existence is symbolic rather than historical.
The 35 Buddhas stand for the many aspects of buddha nature, being the wisdoms, virtues and qualities of a Buddha represented individually in the form of symbolic figures. These buddhas are the divine teachers and monarchs of every mythology. They were "once living men, great adepts and Saints, in whom the 'Sons of Wisdom' had incarnated, and who were, therefore, so to speak, minor Avatars of the Celestial Beings - eleven only belong to the Atlantean race, and 24 to the Fifth race, from its beginnings." (The Secret Doctrine, II. 423.)
"Confession" is not used in the Christian sense of forgiveness of sin. If a young mendicant confesses to his guru some "sin" or personal hangup, he does not seek forgiveness, but insight, and strength to rid his soul "of the thorns of deceit, misapplied austerities, and wrong belief, which obstruct the way to final liberation and cause an endless migration of the soul."
These thirty five Tathagatas are the deities who preside over a penitential rite (Tib.: ltung bzhags ) based on the Upalipariprccha, which forms a part of the Maharatnakuta Sutra. Because of the widespread practice of this penitential rite, these thirty five Buddhas became an extremely popular motif in Thangka painting, developing two currents in their iconographical representation. One is based on a manual by Tsong Kha Pa called the " Sangs rgyas so lnga´i mngon rtogs dang lha sku´i phyag tshad" , while the other derives from the Bodhypattidesanavrtti attributed to Nagajuna. The former is used chiefly by the dGe lugs pa, while the latter is used by the other three main schools of Tibetan Buddhism, but there are exceptions to this general rule.