CodeIgniter - Utilisation of "new" to create
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I have a philosophic question on CodeIgniter, and the role of its model on the utilisation of "new" to instance something.

It looks to me that the idea, is that you use for example to use let say a model of a book

    $this->load->model("book_model")

instead of 

    new book_model

What I mean, is that since you load only once the book_model, you will have only one instance of a book_model, and if you want to model multiple books, you will use a createNewBook function in the book_model, instead of going through the _construct fonction after using "new".

Is it right to see it like this? I mean to consider that I use the same instance of book_model and a function inside it "initiateBook"? Should we consider to never use "new" in CodeIgniter?