The 20th century witchcraft revival saw a lot of effort put into good PR - and necessarily so. As witchcraft emerged from under a shadow of mistrust to become something more socially acceptable, the idea that witches are basically good people was something we all heard a lot about.
We do good, kind, benevolent white magic, not nasty evil black path stuff.
Or as it's more often put, an it harm none, do what you will.
The truth of magical history is not as squeaky clean. There is plenty of evidence that people in the past - who may or may not have self identified as witches - did a lot of cursing. As writing it down is a popular method, there's some pretty clear and detailed evidence out there for curses. Whether we like them or not, they are part of the history of people doing magic, and for that reason alone we ought to be talking about them.
This a brave book, in that it tackles the issue of cursing head on, and pulls no punches. It looks at how, and why and when. Cursing is not as ethical simple as you might first think. When there is no justice available, seeking a bit of poetical justice by magic has, if you will excuse the turn of phrase, a certain charm. When the system is corrupt, when someone has wronged you and holds all the power, when you have no witnesses to support you, then terrible things can be got away with. There's a case to make for using curses at times such as these.
There's also a saying that if you don't know how to curse, you don't know how to cure. A person who will only deal with love and light and unicorns is perhaps not equipped to deal with everything they might encounter in this life. To understand how and when and why people resort to curses is to know something of the human condition that can serve you well, regardless of whether you want to be working with deliberate malevolence.
this is not the most comfortable book ever written - and rightly so, but if you are interested in traditional magic, it's well worth a read.