Here is a quote from Schelling that I think clearly situates the debate between Idealism and so-called Realism (“so-called” because Idealism is not necessarily opposed to Realism). In the excerpt ( it is only necessary to read the first part) Schelling is defining the concept of transcendental philosophy. In order to do this Schelling begins by identifying the twin poles from which the problem of knowledge is attacked: the objective (nature) and the subjective (mind). Schelling makes the point that in the act of knowing i.e experientially, we are unable to determine which, the objective or subjective, has priority. In normal experience, the consciousness of the objective and subjective is simultaneous therefore we cannot determine from mere experience which has priority. This is to say that in normal experience I’m conscious that “there exists things without me ( stones, rocks, cars, trees etc)”; and I am also conscious that “I am perceiving the things.” This experience is simultaneous and does not by itself tell us which has priority. I am not conscious of “things without us (matter)” then later conscious of myself, or vice versa, I am not first conscious of myself then conscious of matter but I am conscious of both simultaneously. As result of this, we are unable to determine in the act which has priority. In order to determine this, we must theorize or philosophize this very act of experience, knowing.