הלכה על ברכות 107:14

And after this we will speak more generally about the rabbinic obligation of blessings. And that is: To recite a blessing before eating and drinking of anything that has any [good] taste to the palate - and so too, afterwards. And so [too,] they obligated us to recite a blessing over every good smell that we smell before smelling, but not after it. And the general principle of the thing is that they fixed a blessing on everything from which the body derives pleasure. And so [too,] did they obligate us (Pesachim 7b) to bless God and to admit [His goodness] over all the good that He has granted us in our doing His precious commandments. And they said that we recite a blessing over them before their doing. And the matter, according to my opinion, is like the reason mentioned adjacently about the reading of the Torah. And so [too,] they obligated us to recite blessings in praise of the Creator over His very mighty deeds, as is mentioned in the chapter [entitled] Haroeh (Berakhot 54a).