Musar for Yevamot 149:19
וניקב לא מוליד והא ההוא גברא דסליק לדיקלא
WHAT IS TERMED A PEZU'A? Our Rabbis taught: What is termed a pezu'a dakkah? A man both of whose stones were wounded or even only one of them; even though they were only punctured, crushed, or simply defective. Said R. Ishmael son of R. Johanan b. Beroka: I heard from the mouth of the Sages at the Vineyard<span class="x" onmousemove="('comment',' The College. So called because the students were sitting in rows arranged like the vines in a vineyard. ');"><sup>46</sup></span> at Jabneh that one having only one stone is a natural born eunuch<span class="x" onmousemove="('comment',' [H] lit., 'a eunuch through heat', i.e., fever, illness (v. Golds.) or 'a eunuch of the sun', i.e., from birth when the child first saw the sun (v. Jast.). ');"><sup>47</sup></span> and is, therefore, a fit person. How could it be said that such a person is a natural born eunuch!<span class="x" onmousemove="('comment',' The former surely might be the result of an accident! ');"><sup>48</sup></span> — Say rather, he is like a natural born eunuch and is, therefore, fit.<span class="x" onmousemove="('comment',' The prohibition being restricted to the wounded or crushed. ');"><sup>49</sup></span> Is [a man whose stones are] punctured incapable of procreation? Surely, a man once climbed up a palm tree