Donaldson made quite an achievement explaining Einstein's theories here. Try explaining one, say, the theory on gravity, to a 10 year-old or to a group of high school students whose English is somewhere below intermediate level. Then after that, if you succeed, move on to the next one that contains the famous energy equation. By the time you reach the general theory of relativity you'd probably be starting telling yourself you deserve a nice vacay somewhere.
The author did a decent job explaining how space and time are the same, how gravity warps space, and how in the universe "pushing" is done more than "pulling". He did all that while telling about Einstein's life from birth to death, and the state of science in Europe before and after the Second World War. That is not an easy task, considering that it was all written on just 82 pages. There is, obviously, a lot of omission done to achieve this. There are no complex formulas and almost no scientific jargon. Just simple, basic English. And yet the result is engaging and educational. The author even ends the book by showing Einstein's theories making possible some of the things we see everyday. How GPS devices and satellites use the general theory of relativity for the calculations; how his famous energy equation is used in PET scans, nuclear energy, and lasers.