Virology in order to immunize others. In 1717 Lady Mary Wortley Montagu observed the practice in Istanbul and attempted to popularize it in Britain, but encountered considerable resistance. In 1796 Edward Jenner developed a much safer method, using cowpox to successfully immunize a young boy against smallpox, and this practice was widely adopted. Vaccinations against other viral diseases followed, including the successful rabies vaccination by Louis Pasteur in 1886. The nature of viruses however was not clear to these researchers. In 1892, the Russian biologist Dmitry Ivanovsky used a Chamberland filter to try to isolate the bacteria that caused tobacco mosaic
To the Youth in Western Countries To the Youth in Western Countries On 29 November 2015, Ali Khamenei, the Supreme Leader of Iran, published an open letter addressed to the youth in western countries. It is the second letter of its kind, the first one having been published in January 2015. Both were distributed via his accounts on various social media, including Twitter, Facebook and Instagram, using the hashtag #CommonWorry. The second letter deals with Khamenei's views on the causes of recent terrorism. It was written in response to the November 2015 Paris attacks and other contemporary terrorist actions, such as the Metrojet Flight 9268 crash