A mind is a lot like a journal for several reasons. Let’s start with the obvious. They both start relatively blank with a few basic functions that they perform involuntarily, for example a baby breathes because that is what it is supposed to do. Equally a journal holds the pages together, again, because that is what it is supposed to do. There are no opinions or coherent thoughts in the mind or on the pages. So now we have established that the mind and journal are both blank. For this reason they are also both boring. The thoughts and memories must be rendered onto each before either one starts to come to life. Not that babies are boring; in fact they will keep you on your toes. Yet all babies have similar needs: they all want to be loved, to be fed and to poop. They are as similar to each other as the blank pages of everyone’s journal. It is not until they reach later infancy and toddler hood that they become interesting as individuals. This [Baby-hood (?) I don't know what word you would use here, but you need to make it clearer that the time spent as a baby is the time when this occurs:] is the time when their mind is soaking up things around them. Equally I have never read and interesting book that had no words written in it.

So now that we have started rendering entries in the journal and thoughts in the mind I notice here that there [agghh! "here" and "there" that close together makes your sentence very confusing. A better sentence might read: "Now that we have begun ..., another common trait become apparent"] is another common trait. Each one sees things one sided. In your memories you only remember your version of the story, just as an author only writes their version of the story [you should read a David Foster Wallace novel sometime, but I see your point]. The stories that you tell reminiscent of your childhood will almost certainly differ from the versions that your parents will tell. In your version you are an innocent angel wrongfully accused and in their version you are evil incarnate[, for example; I was an angel and my parents agree :) Seriously, though, be careful about making generalizations like this].

The funny thing about thoughts that are one sided, be it in mind or on paper, is that they can be false. They can both lie. For them to lie it would involve the scratching out of information that is known to be true and possibly the replacing of that knowledge with something else. When the mind is making a memory it can omit certain details, such as things it may wish to forget. A mind can recount a memory so many times with this certain detail out or changed that eventually the mind can’t remember what truly happened. It is the whiteout or eraser marks of the mind. So if this memory is recorded in a journal it is a recorded lie. Those in the future who read the journal entry won’t be getting the full truth. On a more physical side with the journal one could literally use whiteout or erasers. Both the pages of the mind and the pages of the journal can be deliberately altered. [This paragraph is confusing. There are a few lucid sentences, but, on the whole, I think your point gets obfuscated by awkward verbage]

They [A journal and the mind] also both have the capability to add and believe in non-existent information. The [Your] mind can tell itself that something has happened so many times that you believe it to be true. So you are now the owner of a memory of a time or event that never existed for you. You may swear up and down that you were right there when everyone else around you says that you weren’t. Essentially the mind has tricked itself into believing a false to be a truth. Equally, something [a false entry] can be added to a journal, as all entries are and[.] [B]ecause there is no one [else] there to dispute it, it gets recorded and believed as truth even if it is not. So like the mind[,] the journal has tricked its reader into believing the taking place of an event that did not really occur.

Also[,] in the end[,] both will cease to do even their basic involuntary functions. The person will die and stop breathing and the journal will eventually fall into disrepair[,] perhaps losing some of its pages. You may question that last argument because a book can be preserved just like many other famous documents that are decorating the inside of museums. True, it can be preserved, but for how long? Eventually, even the Declaration of Independence won’t be around one million years from now.