[א] אילו אמר "מקוה מים יהיה טהור" – יכול אפילו מלא בכתפו ועשה מקוה בתחלה יהא טהור – תלמוד לומר "מעין"; מה מעין בידי שמים אף מקוה בידי שמים. אי מה מעין שאין בו תפיסת ידי אדם אף מקוה שאין בו תפיסת ידי אדם, יצא המניח קנקנים בראש הגג לנגבם ונתמלאו מים… תלמוד לומר 'בור'. אי בור יכול אפילו בור שבספינה יהיה טהור? תלמוד לומר "מעין" – מה מעין שעיקרו בקרקע אף מקוה שעיקרו בקרקע. אי מה מעין מטהר בכל שהוא אף מקוה מטהר בכל שהוא! תלמוד לומר "אך מעין" – המעין מטהר בכל שהוא והמקוה במ"ם סאה.
1) (Vayikra 11:36) ("But a spring or a pit where waters are gathered shall be clean; and he who touches their carcass [the carcass of the animals mentioned above] shall be tamei.") If it were written (only) "a gathering of waters shall be clean," I would think that even if he filled up (containers of water and carried them) on his shoulder and made a mikvah ab initio that it would be valid; it is, therefore, written "a spring" — Just as a spring is made by Heaven, so a mikveh must be made by Heaven. — But if so, I would say: Just as there is no involvement of man in a spring, so there must be no involvement of man in a mikveh — to exclude one's placing his vessels on the roof to dry, their filling up with (rain) water, (their breaking, and filling up a pit, in which instance I would think that the water is considered "drawn" and that the pit is pasul as a mikvah) — it is, therefore, (to negate this,) written "a pit." If so, I would think that a pit in a boat (i.e., a cavity into which sea water is admitted) would be valid; it is, therefore, written "a spring." Just as a spring is ground-based, a pit, too, must be ground-based. If so, I might think that just as a spring cleanses with any amount (that covers the object), so a mikvah cleanses with any amount. It is, therefore, written "But a spring" — a spring cleanses with any amount, but a mikvah requires forty sa'ah.
[א] אילו אמר "מקוה מים יהיה טהור" – יכול אפילו מלא בכתפו ועשה מקוה בתחלה יהא טהור – תלמוד לומר "מעין"; מה מעין בידי שמים אף מקוה בידי שמים. אי מה מעין שאין בו תפיסת ידי אדם אף מקוה שאין בו תפיסת ידי אדם, יצא המניח קנקנים בראש הגג לנגבם ונתמלאו מים… תלמוד לומר 'בור'. אי בור יכול אפילו בור שבספינה יהיה טהור? תלמוד לומר "מעין" – מה מעין שעיקרו בקרקע אף מקוה שעיקרו בקרקע. אי מה מעין מטהר בכל שהוא אף מקוה מטהר בכל שהוא! תלמוד לומר "אך מעין" – המעין מטהר בכל שהוא והמקוה במ"ם סאה.
1) (Vayikra 11:36) ("But a spring or a pit where waters are gathered shall be clean; and he who touches their carcass [the carcass of the animals mentioned above] shall be tamei.") If it were written (only) "a gathering of waters shall be clean," I would think that even if he filled up (containers of water and carried them) on his shoulder and made a mikvah ab initio that it would be valid; it is, therefore, written "a spring" — Just as a spring is made by Heaven, so a mikveh must be made by Heaven. — But if so, I would say: Just as there is no involvement of man in a spring, so there must be no involvement of man in a mikveh — to exclude one's placing his vessels on the roof to dry, their filling up with (rain) water, (their breaking, and filling up a pit, in which instance I would think that the water is considered "drawn" and that the pit is pasul as a mikvah) — it is, therefore, (to negate this,) written "a pit." If so, I would think that a pit in a boat (i.e., a cavity into which sea water is admitted) would be valid; it is, therefore, written "a spring." Just as a spring is ground-based, a pit, too, must be ground-based. If so, I might think that just as a spring cleanses with any amount (that covers the object), so a mikvah cleanses with any amount. It is, therefore, written "But a spring" — a spring cleanses with any amount, but a mikvah requires forty sa'ah.