Douglass brings out some of the most basic thematic elements in the first chapter.  The fact that he struggles to determine how old he is represents the idea that the slaveowner holds power over the slave in the denial of his most base components of identity. This is also seen in how Douglass remembers little of his mother. Douglass sets out to show slavery as a dehumanizing experience.  It is one that Douglass believes is predicated on the idea that the slave not know who he is and not be aware of his own identity.  Having this withheld from the slave by the master ensures the continued subjugation of the former at the hands of the latter.  At the same time, Douglass brings out the cruelty in slavery with the revelation that his father was the plantation owner.  In this, Douglass establishes the fundamental cruelty that lies at the heart of slavery.  This is not something to be seen in political terms or even in something to be viewed from a religious point of view.  Douglass seeks to develop the theme of the cruelty that is intrinsic to slavery.  In Douglass' frame of reference, anyone who practices it or condones it in any way is a party to such cruelty.  Through the tenets of denying the basic identity of the slave, as Douglass shows in his own life through the first chapter, he establishes the groundwork for this theme.