I'm hoping I get away with what I'm calling PhARTography. I couldn't find a terribly interesting offering to present so thought to sketch one (badly), photograph it and then paint it in Photoshop (also badly). Here is the result.
Back in the late 1700's medical scientists realised that milk maids didn't catch smallpox if they had previously contracted the much less dangerous cowpox.
In time the practice of proactively introducing people to an antigen in order to stimulate adaptive immunity to pathogens became known as "vaccination" (Vacca = cow in Latin)
I saw these fresian heifers in a pasture close to my Bozeat home earlier in the week, so I took a walk down there this afternoon for a look-see, they were friendly if a little skittish (well, they are still very young) this one was the least bothered with my intrusion.