You must remember that these are not two minds. They are merely two spheres of activity within one mind. Your conscious mind is the reasoning mind. It is that phase of mind, which chooses. For example, you choose your books, your home, and your partner in life. You make all your decisions with your conscious mind. On the other hand, without any conscious choice on your part, your heart is kept functioning automatically, and the process of digestion, circulation, and breathing are carried on by your subconscious mind through processes independant of your conscious control.
Your subconscious mind accepts what is impressed upon it or what you consciously believe. It does not reason things out like your conscious mind, and it does not argue with you controversially. Your subconscious mind is like the soil, which accepts any kind of seed, good or bad. Your thoughts are active and might be likened unto seeds. Negative, destructive thoughts continue to work negatively in your subconscious mind, and in due time will come forth into outer experience which corresponds with them.
Remember, your subconscious mind does not engage in proving whether your thoughts are good or bad, true or false, but it responds according to the nature of your thoughts or suggestions. For example, if you consciously assume something as true, even though it may be false, your subconscious mind will accept it as true and proceed to bring about results, which must necessarily follow, because you consciously assumed it to be true.
Extract from the book “The Power of Your Subconscious Mind” by Joseph Murphy