How many tests were used to verify de Vinci 's work " Lady with an Ermine " ?
The ermine , a stoat in its winter coat , was a traditional symbol of purity because it was believed an ermine would face death rather than soil its white coat : In his old age , Leonardo compiled a bestiary in which he recorded:MODERATION The ermine out of moderation never eats but once a day , and it would rather let itself be captured by hunters than take refuge in a dirty lair , in order not to stain its purity .