First of all its important to define the word immanence, which means remaining within or operating within. To strart of with, th eplane of immanence does not have a particular form, it's not finished the same way reality as we know it is not a finished product. According to D&G the plane of understanding is determined by the conceptual framework. Its important to undestand that philosophy begins wiht the creation of concepts. According to D&G the plane of immanence is neither a concept nor the concept of all concepts, is not a concept that is or can be thought, but its rather the immage of thought and this implies a rather strict dividion between fact and right .The plane is formless while concepts are defined as absolute volumes.
D&G suggest that the whole history of philosophy can be regarded or seen as an attempt to institute a plane of immanence. Philosophers have a tendency of claming that the notion of immanence is relative to something, this only results in teh confusion of the plane of immanence with a concept. One important distinction one has to make is that concepts do not correspond to anything, they simply resonate.
According to Sartre, when immanence is not immanent to something but itself, then it is only possible to speak of a plane of immanence. The plane then can perhaps be radical emparisism.therefore the plane presents events that are expressed in the form of words as concepts. But what does this mean, radical empiricism? "When immanence is no longer immanent to something other than itself it is possible to speak of a plane of immanence.Such a plane is, perhaps, a radical empiricism"pg 47.
Radical empiricism would therefore be an operation which consists in liberating immanence, returning it to its own movement. Sartre refers to this operation as transcendental empiricism, whereby one establishes a plane of immanence, when the plane of immanence is determined as transcendental field.
