Did you think that UFOs decided to suddenly begin to hit the Earth only in the 20th century, since the 1940s, when they were spotted? Does that mean that life elsewhere made its appearance here only recently? No, UFOs were callers much earlier.

The evidence is out on that one. Even in the beginning of the last century, "mysterious airships" could be seen over UK. That spurred Winston Churchill to order a probe into it. 

Here is another 18th century Mathematics book, whose cover shows a UFO emerging from the clouds and racing over the sea, surrounded by lightning bolts.

It is a Latin book on Mathematics, titled 'Liber De Coloribus Coeli, Accedit Oratio Inauguralis De Deo Mathematicorum Principe', written by Johann Caspar Funck, published 1716. Recently, the book got republished on Google Books. 

Now why does the cover depict the flying saucers---disc-shaped objects that look exactly like the ones that have been seen recently?

It was the Blogger Reid Moore who spun the theory that the cover image is that of a UFO. In a blog on culture website niume, Moore wrote: "The illustration depicting what is generally considered to be a 'classic' UFO shape bears more scholarly investigation. But it does support the theory that UFOs have been witnessed and chronicled throughout history. What is unusual in this case is the similarity to the 'modern' consensus of what unidentified flying objects look like."

He explained that the "aerodynamically rounded shape" of the saucer, as well as the dramatic effect of the UFO emerging from storm clouds and going forward through "electrical phenomenon, most likely a magnetic propulsion system" are all indicative of something closer to modern sightings.

He added that strange flying machines have been exhibited in art for centuries. However, what makes this image stand out is the 'classic' UFO shape. Considering that it is 300 years old, it makes us draw our conclusions. 

"Is it proof that flying saucer UFOs have been visiting Earth since the early 1700s? At the very least, it's evidence that some people in the past seem to have thought so," he wrote.

Certainly, the clues do point in that direction. Moreover, this is 'only' 300 years old. Perhaps flying saucers have been hitting the Earth much earlier, though they were never depicted?