Reference for Bava Kamma 12:7
לעולם דאפקרינהו ולא דמי לבור מה לבור שכן תחילת עשייתו לנזק תאמר בהני שאין תחילת עשייתן לנזק
who maintains that we deduce [the law governing] all nuisances from Pit, they are [again] equivalent to Pit? — Indeed they were abandoned, still they are not equivalent to Pit: Why [is liability attached] to Pit if not because of its being from its very inception a source of injury? How then can you assert [the same] in the case of those which are not sources of injury from their inception? — Ox, however, will refute [this reasoning]. But [you may ask] why [is liability attached] to Ox if not because of its nature to walk about and do damage? — Pit will refute [this reasoning]. The argument is [thus endlessly] reversible [and liability<span class="x" onmousemove="('comment',' Even in the case of the wall and the tree. ');"><sup>5</sup></span>