In the Preface, he writes:
If I had any motive more prominent than the rest (beyond promoting the cause of truth, which, I trust, will always be the principal) for publishing this work, it was a desire to injure those harpies who gather together scarce books of science, and hide them from the perusal of mankind, merely for the sake of gain, which, after all, can be but trifling: men like these are the enemies of knowledge, and ought to be severely punished in every civilized nation. This treatise will render most of their hoards comparatively useless, for I have been careful to insert the substance of all they contain relating to astrology, whether true or false, adding occasionally some remarks of my own to distinguish the latter as far as I am able, that every student may be enabled to found his own conviction on his own experience.
Rather than the short, arid articles typical of specialized dictionaries, Wilson offers extensive entries on (Primary) Directions, Faces, Figures, Forms of the Body, Horary Astrology, Marriage, Part of Fortune, Weather, the judgment of Revolutions, Progressions, Ingresses, Riches, Promittors, as well as many more.
A few years after this book, the author published his translation of Ptolemy's Tetrabiblos, one of only a handful of men to have done so.
The Dictionary of Astrology is a book of surprises. It will repay study.