Rambam- The Singularity of G-D- Yisodei Hatorah seventh halacha

The most important detail in understanding G-D is His uniqueness. The fact that there is nothing else like Him in existence, in and of itself, tells us something. The Rambam says (first half of the halacha),
אלוה זה אחד הוא ואינו שנים ולא יתר על שנים. אלא אחד. שאין כיחודו אחד מן האחדים הנמצאים בעולם. לא אחד כמין שהוא כולל אחדים הרבה. ולא אחד כגוף שהוא נחלק למחלקות ולקצוות. אלא יחוד שאין יחוד אחר כמותו בעולם
" This G-D is singular, there is not two of Him or more than two, rather He is a type of singularity that does not exist with any other singular being in the world. He is not a singular being like that of a being that is made up of many singular beings, nor is He a singular being like a body that is divided into many individual parts with limits. Rather His singularity is not like that of any other singularity found in the world."

The Rambam's point here is that he is trying to describe the oneness of G-D. However, it is impossible for the human mind to comprehend the concept of G-D's singularity, therefore the Rambam must describe this intangible idea through what it is not. By doing this the Rambam must define the different types of singularity that exist in the world. The first type of singularity described is one that is made up of many other microcosms of the greater singularity, similar to a species or a country. A species is made up of many entities that share a common goal or existence and a country is made of of individuals that also share a common goal or existence. However, in both of these situations the species or country is not controled by one thought process, but rather by several. Also, the Rambam points out that G-D is not even the type of singularity that consists of many parts but is controlled by one intellect like a body, rather His singularity is even greater than this description.

The Rambam continues the description of G-D by saying (second half of the halacha),
אילו היו אלוהות הרבה היו גופין וגויות. מפני שאין הנמנים השוין במציאותן נפרדין זה מזה אלא במאורעין שיארעו בגופות והגויות. ואילו היה היוצר גוף וגוייה היה לו קץ ותכלית שאי אפשר להיות גוף שאין לו קץ. וכל שיש לגופו קץ ותכלית יש לכחו קץ וסוף. ואלהינו ברוך שמו הואיל וכחו אין לו קץ ואינו פוסק שהרי הגלגל סובב תמיד. אין כחו כח גוף. והואיל ואינו גוף לא יארעו לו מאורעות הגופות כדי שיהא נחלק ונפרד מאחר. לפיכך אי אפשר שיהיה אלא אחד. וידיעת דבר זה מצות עשה שנאמר ה' אלהינו ה' אחד: 
" If there were many G-D's (similar to a species or country) then they would have to have a body and a form, because entities that are equal in existence can only be if they also happen to have bodies and forms [to separate themselves from each other]. And if the creator were to have a body and form then He would also have limits and an end for it is impossible for a body to exist that has no limits. Also, anything that has limits and an end, its power also has limits and an end. However, G-D, bless his name, has powers without limits or an end since the sphere (earth or sun) rotates continuously [through His power], therefore his power must not be a power from a [physical] body. [Since we proved that G-D] does not have a body it must be that no occurrence occurred for [G-D to have] a body that separates Him from another [god]. Therefore, it is impossible that any other gods exist other than Him. To know this concept [of G-D's singularity] is a positive commandment that it says in the pasuk, 'G-D our lord G-D is One.'"

The Rambam here is describing why it must be that G-D is singular. The first half of this halacha points out that G-D is singular and he tries to describe that singularity. However, the second part of this halacha describes why G-D must be singular. He points out that G-D's power is contingent on the fact that He is singular. G-D's power and existence can only be possible as the singular entity that he describes in the first half of the halacha. The commandment of "G-D is our lord, G-D is singular," is only fulfilled when one is able to understand G-D's full power as a single entity. One can not understand G-D's existence through the singular entities that we can comprehend, but rather only through the negation of the singular entities that we recognize.