כא ורבי זירא מאי טעמא לא אמר כרבה אמר לך מחיצות
21 continually takes him from the beginning of four cubits and puts him down at the end of the four cubits.<span class="x" onmousemove="('comment',' So that he did not rest for one moment in any particular spot. Not having acquired any four cubits as his Sabbath abode, all the ship is regarded as his home. Aliter: Whenever the man lifts up his foot the ship carries him a distance of four cubits before he can put it down, and he is, therefore, in the position of a man whom gentiles have forcibly taken out from his four cubits and put in another four cubits and who is always u,kyub entitled to the last four cubits in which he finds himself (cf. Rashi s.v. a.l.) .');"><sup>33</sup></span> What is the practical difference between them?<span class="x" onmousemove="('comment',' Rabbah and R. Zera.');"><sup>34</sup></span> - The practical difference between them is the case where the sides of the ship were broken down,<span class="x" onmousemove="('comment',' Rabbah's reason does not apply while R. Zera's does.');"><sup>35</sup></span> or where one leaps from one ship into another.<span class="x" onmousemove="('comment',' On the Sabbath. Since the man did not occupy a place in the latter ship while it was yet day he is not allowed, according to Rabbah, more than four cubits. According to R. Zera he may walk all through the ship.');"><sup>36</sup></span> But why does not R'Zera give the same reason as Rabbah? - He can answer you: The sides<span class="x" onmousemove="('comment',' Of a ship.');"><sup>37</sup></span>