This is certainly one of Pope's more philosophical works, compared to the more whimsical The Rape of the Lock, for example. In this text, Pope seeks to explain and define the position of man in relation to the created order through reference to the Great Chain of Being, which is an order that structures creation in accordance with the divine plan of God. Pope uses this overarching framework to develop his ideas about how the universe is structured and what man's place in it is. He argues that the apparent chaos or disorder that we see in the universe are in reality smal parts of a larger perfected order that we are not able to understand from our limited perspective. He further argues that the suffering we experience is a result of our own pride rather than the created order.
This external order is mirrored by an internal order which features a balance between desire and judgement. We need to strike a balance between these two important aspects to live rightly. Pope goes on to argue that goodness and evil are states that are not to be found in desire and judgment, they only arise out of an incorrect balance between them.
Another form of order that this text explores is the order that we are encouraged to strive for in human society. If we are able to imitate the order that is to be found in nature and also the internal rational self-love that we are to strive for in ourselves, we can sustain a society that is based on stability as well. What ruins this balance is the favouring of a particular religion or structure of government in exchange for general moral principles. Our place in the Great Chain of Being enables us to achieve our goal, which is happiness and peace, but only when we learn to eschew our pride and submit willingly to Providence.