Of the Principles of Human Knowledge

In George Berkeley's Of the Principles of Human Knowledge, Berkley explains that one only perceives ideas through the mind.  He extends his explanation further by stating that only ideas can not exist without the mind.  This is true.  How can one perceive anything without having a mind in the first place.  However, he attempts to defend his statement by saying that matter can not exist without being perceived and this is not the case.  Berkeley attempts to defend himself by stating in point 17.  "If we inquire into what the most accurate philosophers declare themselves to mean by material substance; we shall find them acknowledge, they have no other meaning annexed to those sounds, but the idea of being in general, together with the relative notion of its supporting accidents.  The general idea of being appearth to me the most abstract and incomprehensible of all other; and as for its supporting accidents this, as we have just now observed, cannot be understood in the common sense of those words; it must therefore be taken in some other sense, but what that is they do not explain."  He later asks how is it possible for people to know that solid, figured moveable substances exist without the mind.  So by stating this, it is possible to claim that everything outside of the room I am in could potentially not exist and this is certainly not the case.  If I were to call someone, does only their voice exist?  What if I were hallucinating? Do the hallucinations exist?  There appears that Berkeley's theory has several holes that do not follow up.  He later explains that there are spirits (or I am assuming God) that can perceive only through the senses and they always are view which can not always be seen by humans.  In point .35 he states that "I do not argue against the existence of any one thing that we can apprehend, either by sense or reflection. That the thing I see with mine eyes and touch with my hands do exist, really exist, I make not the least question.  The only thing whose existence we deny, is which philosophers call matter and corporeal substance.  And in doing of this, there is no damage done to the rest of mankind, who, I dare say, will never miss it".  It is ironic that he stated earlier that the other philosophers  can not explain material substance; however he wants people to except his idea because why not?  There is no harm in his belief.  So people just to except that matter only exists because spirits and humans are able to perceive them.  There is no proof and his theory completely defeats the purpose of Chemistry.  I feel that Berkeley was correct stating that one can only perceive through their mind; however, the rest of his theory is not based upon anything and relies upon spirits or God as an explanation for everything that exist and thus can not be proven.