All the philosophies of the world have failed to explain the existence of Evil. The Vedas and Upanishads too failed there. The Upanishads said All is Brahman. Having said so, it amounts to saying that Evil too is Brahman. Sri Aurobindo devotes a full chapter of about forty pages to explain the origin of Error, Mistake, Falsehood and Evil. Brahman has not created in the world anything but Ananda. But evil, cruelty, tyranny etc. are realities of life. He says evil is real to the ego and has no inherent reality in itself. For one who has come out of ego, there is no evil to be seen. Wars are horrendous for us where millions of lives are destroyed. Once you come out of ego, you see war is Nature's method to hasten the process of evolution and the souls of those who die, die in bliss.
We know of the positive and negative. We accept the positive and denounce the negative. Sri Aurobindo says that there is nothing negative. Positive and negative are two parts of a single whole. Experience of the negative gives the keener and fuller intensity to the positive to enjoy the whole. Experienced people in business say unless you have lost money, your experience will be incomplete. To us, the convict is a person to be avoided, because he is negative. During the 19th century, England and other countries sent their convicts to Australia. Today Australia is one of the richest nations in the world. It is the convicts who built up a prosperous civilisation. Singapore is rich. Originally, it was Indian convicts who built up Singapore. If convicts are evil, we must accept that good comes out of evil.
If you are past forty, try to recollect in your childhood children branded unanimously evil. Today you will find most of them, maybe all of them better placed in life than the children described as Good. Indian wisdom enjoins on us NOT to inquire into the origin of a Rishi or a river. Valmiki was a dacoit. Robert Clive was an evil youth. He founded the world's largest empire. Sri Aurobindo's yoga is a yoga of transformation. He calls Evil the greater good. He wants man to surrender to God so that God can transform the ‘Evil' of the world into good. He who can see the Truth here and live up to it can rise to the great heights of life, as he will recognise the deepest evil in himself.