To explore the role that envy plays in our use of social media, Kross and his team designed a study to consider the relationship between passive Facebook use – “just voyeuristically scrolling,” as he puts it – and envy and mood from moment to moment. Participants received texts five times a day for two weeks, asking about their passive Facebook use since the previous message, and how they were feeling in that moment. The results were striking, he says: “The more you’re on there scrolling away, the more that elicits feelings of envy, which in turn predicts drops in how good you feel”.

No age group or social class is immune from envy, according to Andrew. In her consulting room she sees young women, self-conscious about how they look, who begin to follow certain accounts on Instagram to find hair inspiration or makeup techniques, and end up envying the women they follow and feeling even worse about themselves. But she also sees the same pattern among older businessmen and women who start out looking for strategies and tips on Twitter, and then struggle to accept what they find, which is that some people seem to be more successful than they are. “Equally, it can be friends and family who bring out those feelings of envy, around looks, lifestyle, careers and parenting – because somebody is always doing it better on social media,” she says. How much worse would it have been for Shakespeare’s Iago, who says of Cassio: “He hath a daily beauty in his life / That makes me ugly,” if he had been following his lieutenant on Instagram?