certain prior begged him to come and fresco the
walls of his convent. This prior was very famous
for making a most beautiful and expensive blue
colour which he was anxious should be used in the
painting of the convent walls. He was a mean,
suspicious man, and would not trust Perugino with
the precious blue colour, but always held it in his
own hands and grudgingly doled it out in small
quantities, torn between the desire to have the
colour on his walls and his dislike to parting with
anything so precious.

As Perugino noted this, he grew angry and
determined to punish the prior's meanness. The next
time therefore that there was a blue sky to be
painted, he put at his side a large bowl of fresh
water, and then called on the prior to put out a
small quantity of the blue colour in a little vase.
Each time he dipped his brush into the vase,
Perugino washed it out with a swirl in the bowl at
his side, so that most of the colour was left in the
water, and very little was put on to the picture.

`I pray thee fill the vase again with blue,' he said
carelessly when the colour was all gone. The prior
groaned aloud, and turned grudgingly to his little
bag.

`Oh what a quantity of blue is swallowed up by
this plaster!' he said, as he gazed at the white wall,