First word - this isn't a book that uses methods of 'science' despite the title stating so - it is a book on what I would term 'personal philosophy'.
The Science Of Getting Rich was published in 1910 - well over a hundred years ago, in a world vastly different from what we view today. However, after reading it, I realised that the philosophy from this book has found its way to many books over the ages, Napoleon Hill's Think and Grow Rich, written in 1937, Joseph Murphy's 1963 book, the Power of your Subconscious Mind, and even the relatively recent 2003 book by Rhonda Byrne, 'The Secret' liberally borrows from these ideas . Of course, had I not read all these books previously, I wouldn't have realised this.
The basic premise of this book can be summarised in a few sentences that repeated many times in the book.
"There is a thinking stuff from which all things are made, and which in its original state permeates, penetrates and fills the interspaces of the universe.
A thought in this substance produces the thing that is imagined by the thought.
Man can form things by his thought, and by impressing his thought upon formless substance can cause the thing he thinks to be created."
Some of the best quotes and thoughts from the book:
"Give every man more in use value than you take from him in cash value; then you are adding to the life of the world by doing every business transaction" - The idea behind this thought is that there is a long of value you can provide in every business transaction it it should be perceivably greater than the money that is paid for it for succeeding in business.
Feel Gratitude for all that you have and receive - Without that sense of gratitute, you cannot keep at bay the thought of dissatisfaction for the way things are. Exercising gratitute will never fail to strengthen your faith and renew your purpose.
"Whatever is it that ye ask for when you pray, believe that ye will receive them and ye will have them (this is taken straight from the Christian Bible)" - The line of thinking here that when you really want something believe you will receive it and act like you already did and you will receive it eventually.
"The poor do not need charity, they need inspiration" - Providing charity is like providing a load of bread to keep the poor alive in their wretchednes but inspiration is what will cause them to rise out of misery. The best thing you can do for the poor is to provide them with the right amount of inspiration to do things for themselves which has far more reaching effects than charity.
"The very best thing you do do for the whole world is to make the most of yourself" - By being the best you can be, you are somebody who becomes constructive to the world in itself.
Note: There are a few things I found disagreeable in the book though especially the advise to NOT read anything else apart from this book (found that a bit ludicrious). The book can get a bit overbearing at times but all in all, it is still worth reading for some good concepts.
Another thing to note is that you might find these concepts redundant if you have already read any of the other 3 books mentioned above. Personally speaking though, I found 'Think and Grow Rich' the most fleshed out one for understanding the common body of ideas discussed in all these books.