As we have previously discussed before, Letters On the English is a series of essay by Voltaire based on his experience of living in England between 1726 and 1729. It is in a sense an attack on the French system of governance and as such the French heavily censored this.
In the 11th such letter or essay, Voltaire argues in favor of the English practice of inoculation. Continental Europe was largely against this treatment. It is thought this letter is in response to the 1723 Parisian small pox epidemic. This epidemic is thought to have killed 20,000 people.
In Letters On the English, Letter XI On Inoculation by Voltaire may be read here:
http://www.bartleby.com/34/2/11.html
An introduction to Voltaire’s philosophy can be found here:
ALOHA PROMISES FOREVER 