The Goods and the Ills explained simply

There was a time in the youth of the world when Goods and Ills entered equally into the concerns of men, so that the Goods did not prevail to make them altogether blessed, nor the Ills to make them wholly miserable. But owing to the foolishness of mankind the Ills multiplied greatly in number and increased in strength, until it seemed as though they would deprive the Goods of all share in human affairs, and banish them from the earth. The latter, therefore, betook themselves to heaven and complained to Jupiter of the treatment they had received, at the same time praying him to grant them protection from the Ills, and to advise them concerning the manner of their intercourse with men. Jupiter granted their request for protection, and decreed that for the future they should not go among men openly in a body, and so be liable to attack from the hostile Ills, but singly and unobserved, and at infrequent and unexpected intervals. Hence it is that the earth is full of Ills, for they come and go as they please and are never far away; while Goods, alas! come one by one only, and have to travel all the way from heaven, so that they are very seldom seen.