One’s philosophy of life is something that is typically discussed in an autobiography. This is basically what the author thinks about life in general, and how they should live. This is always very important to the story told in an autobiography, and needs to be told in a way that makes sense to the reader.
I don’t think that the philosophy of life should always be told early in the autobiography. I think it makes a lot more sense for the philosophy of life to be explained, bit by bit, in the story of the autobiography. Then, you aren’t overwhelmed with information, and it feels like you are discovering information about the author, rather than it being told to you. It feels more authentic to experience the information in a gradual way. This is especially true, because as the author grows and develops their philosophy of life, you get to see how it has changed over the years, and how it came to be what it is, instead of being stated like a simple fact.
In short, I think that the philosophy of life should be told how the author learned it. An authentic experience of growth, both for the reader, and for the author. I think it is a bit unintuitive to lecture to the reader blandly about how one thinks, when that very thing is going to be told slowly and thoroughly without that long introduction.