Early forms of Germanic religion are known exclusively from archaeological remains and can therefore only be interpreted on the basis of comparative studies with other religions or through the evaluation of Scandinavian literature, who, as the last converts among the practitioners of Germanic religion, maintained a written account of their religion into the Middle Ages. In addition to the rich archaeological finds, like the evidence of a widespread veneration of a fire god, there is also linguistic evidence attesting to Germanic religious practices. Description of the oldest forms of the Germanic religion are based on uncertain reconstructions, which in turn are based on comparisons with other material. Archaeological findings suggest that the Germanic peoples practiced some of the same 'spiritual' rituals as the Celts, including sacrifice, divination, and the belief in a spiritual connection with the natural environment around them. Germanic priestesses were feared by the Romans, as these tall women with glaring eyes, wearing flowing white gowns often wielded a knife for sacrificial offerings. Captives might have their throats cut and be bled into giant cauldrons or have their intestines opened up and the entrails thrown to the ground for prophetic readings. Spiritual rituals frequently occurred in consecrated groves or upon islands on lakes where perpetual fires burned.