The supposedly immaterial soul, we now know, can be bisected with a knife, altered by chemicals, started or stopped by electricity, and extinguished by a sharp blow or by insufficient oxygen.

Morality, then, is not a set of arbitrary regulations dictated by a vengeful deity and written down in a book; nor is it the custom of a particular culture or tribe. It is a consequence of the interchangeability of perspectives and the opportunity the world provides for positive-sum games.

People have long assumed that violence is necessary for political change. Rulers never cede power voluntarily, the argument goes, so progressives have no choice but to contemplate the use of force to bring about a better world, mindful of the trade-off between a small amount of violence now and acceptance of an unjust status quo indefinitely.

In many Muslim countries, witchcraft is not only on the books as a crime, but is commonly prosecuted. In 2009, for example, Saudi Arabia convicted a man for carrying a phone booklet with characters in an alphabet from his native Eritrea, which the police interpreted as occult symbols. He was lashed three hundred times and imprisoned for more than three years.

I would argue that nothing gives life more purpose than the realization that every moment of consciousness is a precious and fragile gift.

Since the point of erotica is to offer the consumer sexual experiences without having to compromise with the demands of the other sex, it is a window into each sex's unalloyed desires. Pornography for men is visual, anatomical, impulsive, floridly promiscuous and devoid of context and character. Erotica for women is far more likely to be verbal, psychological, reflective, serially monogamous and rich in context and character. Men fantasise about copulating with bodies; women fantasise about making love to people.

After their return from Babylon, the practice of human sacrifice died out among the Jews, but survived as an ideal in one of its break-away sects, which believed that God accepted the torture-sacrifice of an innocent man in exchange for not visiting a worse fate on the rest of humanity. The sect is called Christianity.