Wallace Wattes is a practically unknown author. The fact of having died before 1930, when exploits the media, and of having written relatively few books, has contributed to that. He has not many followers in the world outside the United States and has not been translated but recently.
However, other authors a little later, as Napoleon Hill, owes him a lot. In the case of Hill, although maybe he never recognized it, show the influence of Wattles in his good known work, Think and Grow Rich, which has been translated to many languages and has influenced to several generations. There is remarkable the influence of the Wattles’ ideas, inclusive whole chapters of that monumental book because of its size) seems to be dictated directly by Wattles.
The work of Hill is big, voluminous, embraces many aspects of the human life, digresses among recommendations of all type that end up inclusive seeming to be contradictory. He goes from the personal finances to the love, in a journey of recommendations inexplicable many times. It is a memory excercise to read that principle book to the end and to be about retaining some idea of those that are contained there.
On the other hand The Science of Becoming Rich or Science of Getting Rich is a concise, elegant and brief book, condensed to the end that seems that if one retired a sentence the work would be unconcluded or weak. It is a focused book, precise, austere, lacking of excessive and of grandiloquent images. Not it is literature. It is the dry and brief expression of a science taken to the end of the minimum thing and of the indispensable thing. They are never necessary many words to tell the truth.