<b>Then Moses sang (Exod. 15:1).</b> May our master teach us whether one may place a plaster upon a sore on the Sabbath? Thus do our masters teach us: It is forbidden to place a plaster upon a sore for the first time on the Sabbath, but if one has placed it there prior to the Sabbath, he is permitted (to change the plaster during the Sabbath). You find that if a man injures someone with a knife, he dresses the wound with a bandage, but the Holy One, blessed be He, does not do so. He heals with what He wounds. And so you find that when they reached Marah, and were unable to drink the water because it was extremely bitter, Moses was of the opinion that the Holy One, blessed be He, would tell him to sweeten it with honey or with pressed figs. Observe, however, what is written there: <i>And he cried unto the Lord; and the Lord showed him a tree</i> (Exod. 15:25). The Holy One, blessed be He, said to him: My way is not man’s way, and you must learn this fact. Thus it is said: <i>The Lord showed him a tree</i>. Actually, the verse does not say <i>and the Lord showed him</i> (<i>vayir’shu</i>) but rather <i>taught him</i> (<i>vayorehu</i>). He taught him His ways.
What kind of tree was it? R. Joshua held: It was a willow tree. R. Nathan declared: It was a bitter ivy tree, while R. Eleazar of Modi’im insisted: It was an olive tree. R. Joshua the son of Karha maintained that it was a cedar tree. Others said that it was the root of a fig tree and the root of a pomegranate tree. In any case, it was extremely bitter. R. Simeon the son of Gamliel said: Come and observe how different the ways of the Holy One, blessed be He, are from the ways of man. Man improves the taste of a bitter thing with something sweet, but the Holy One, blessed be He, improves the taste of a bitter thing by adding something bitter. How does He do that? He places something that causes damage into a thing that is damaged and thereby performs a miracle. For example, And Isaiah said: <i>Let them take a cake of figs and lay it for a plaster on the boil, and he shall recover</i> (Isa. 38:21). Is it not a fact that if you place a cake of figs on a raw piece of flesh, the flesh will decay immediately? This verse illustrates that He places a thing that injures upon something that was injured in order to perform a miracle. Similarly, <i>And he went forth unto the spring of the waters and cast salt therein, and said: “Thus saith the Lord: I have healed these waters; there shall not be from thence anymore death or miscarrying”</i> (II Kings 2:21). Is it not a fact that sweet water into which you put salt water is spoiled immediately? But here He placed a thing that is distasteful into something that was distasteful, and thus performed a miracle thereby. The Holy One, blessed be He, declared unto Moses: Is it not a fact that I am a unique craftsman? Do I not heal with what I wound? If these waters are bitter, I will make them palatable by adding something that is bitter.
Similarly the righteous make amends with the very words with which they rebuke. You know this to be so from the fact that when Moses reproached God, he did so with an <i>az</i> (“then”), as is said: <i>Then as I came to Pharaoh to speak in Thy name, he hath dealt ill with this people</i> (Exod. 5:23). And Moses said: With an <i>az</i> I reproached God, and with an <i>az</i> I shall make amends to Him. Hence, it is said: <i>Then</i> (<i>az</i>) <i>sang Moses</i>.