首楞嚴義疏注經 1.382

1.382

若身外處立中位者，必須約表，何處是中？若不可表，即畢竟無，猶如兔角。若可表示，即成不定，東西南北皆可道故。能表既亂，心應混雜，理應不然。

If one establishes an intermediate position in a location outside the body, one must do so by reference to a marker: where is the middle? If it cannot be marked, then it is utterly non-existent, just like a hare's horns. If it can be indicated, then it becomes indeterminate, because east, west, south, and north can all be designated. Since the marker is chaotic, the mind would have to be confounded, which in principle cannot be so.