Bearing this in mind, we are not surprised to find further traces of a connexion between Sancus and thunderbolts. There was at Rome a _decuria_ of _sacerdotes bidentales_, in close association with the cult of Sancus. Three votive altars are extant, dedicated to the god by this _decuria_[567]; two of them were found on the Quirinal, close to the site of the sacellum Sancus. Now the meaning of the word _bidental_ shows that the _decuria_ had as its duty the care of the sacred spots which had been struck by thunderbolts; such a spot, which was also called _puteal_ from its resemblance to a well fenced with a circular wall, bore the name _bidental_, presumably because two-year-old sheep (_bidentes_) were sacrificed there[568]. Consequently we again have Sancus brought into connexion with the augural lore of lightning, which made it a religious duty to bury the bolt, and fence off the spot from profane intrusion. Yet another step forward in this dim light. A _bidental_ was one kind of _templum_, as we are expressly told[569]; and the temple of Sancus itself seems to have had this peculiarity. Varro says that its roof was _perforatum_, so that the sky might be seen through it[570]. In a fragment of augural lore, apparently genuine though preserved by a writer of late date, the _caeli templum_ seems to have been conceived as a dome, or a ball (_orbis_) cut in half, _with a hole in the top_[571]. We may allow that we are here getting out of our depth; but the general result of what has been put forward is that Sancus = Dius Fidius was originally a spirit or _numen_ of the heaven, and a wielder of the lightning, closely allied to the great Jupiter, whose cult, combined with that of Hercules, had almost obliterated him in historical times. Finally, it would seem that those moral attributes of Jupiter which give him a unique position in the Roman theology as the god of truth, order, and concord, belonged at one period also to Sancus as Dius Fidius; for in his temple was kept the most ancient treaty of which the Romans knew, that said to have been made by Tarquinius Superbus with Gabii, which Dionysius must himself have seen[572], and which he describes as consisting of a wooden _clypeus_, bound with the hide of a sacrificed ox, and bearing ancient letters. Here also was the reputed statue of Gaia Caecilia or Tanaquil, the ideal Roman matron; of which it has been conjectured, rashly perhaps, but by an authority of weight, that it really represented a humanized female form of Dius Fidius, standing to him as the Junones of women stood to the Genii of men, or as Juno in the abstract to Genius in the abstract[573].