Still more important were the magical powers of the Druids--giving or withholding sunshine or rain, causing storms, making women and cattle fruitful, using spells, rhyming to death, exercising shape-shifting and invisibility, and producing a magic sleep, possibly hypnotic. They were also in request as poisoners.[1062] Since the Gauls went to Britain to perfect themselves in Druidic science, it is possible that the insular Druids were more devoted to magic than those of Gaul, but since the latter are said to have "tamed the people as wild beasts are tamed", it is obvious that this refers to their powers as magicians rather than to any recondite philosophy possessed by them. Yet they were clear-sighted enough to use every means by which they might gain political power, and some of them may have been open to the influence of classical learning even before the Roman invasion. In the next chapter the magic of the Druids will be described in detail. The Druids, both in Gaul (at the mistletoe rite) and in Ireland, were dressed in white, but Strabo speaks of their scarlet and gold embroidered robes, their golden necklets and bracelets.[1063] Again, the chief Druid of the king of Erin wore a coloured cloak and had earrings of gold, and in another instance a Druid wears a bull's hide and a white-speckled bird headpiece with fluttering wings.[1064] There was also some special tonsure used by the Druids,[1065] which may have denoted servitude to the gods, as it was customary for a warrior to vow his hair to a divinity if victory was granted him. Similarly the Druid's hair would be presented to the gods, and the tonsure would mark their minister.