That beautiful line is contained in the following passage from the pen of Richard M. Weaver (1910-1963):
It is my contention that a conservative is a realist, who believes that there is a structure of reality independent of his own will and desire. He believes that there is a creation which was here before him, which exists now not just by his sufferance, and which will be here after he is gone. This structure consists not merely of the great physical world but also of many laws, principles, and regulations which control human behavior. Though this reality is independent of the individual, it is not hostile to him. It is in fact amenable by him in many ways, but it cannot be changed radically and arbitrarily. This is the cardinal point. The conservative holds that man in this world cannot make his will his law without any regard to limits and to the fixed nature of things . . . . The conservative I therefore see as standing on the terra firma of antecedent reality; having accepted some things as given, lasting and good, he is in a position to use his effort where effort will produce solid results. (Quoted from Fred Douglas Young, Richard M. Weaver 1910-1963, University of Missouri Press, 1995, pp. 144-145.)
An aphorism of mine supplies the contrast:
With one foot in a past from which he will not learn, and the other in a future that will never be, the leftist stands astride the present — and urinates on it.