Professor Halamish deals extensively with the concepts, the personalities involved especially R. Yosef Karo’s attitude towards the Zohar’s rulings; follows the Gemara when they disagree but follows the Zohar where there is no conflict. Halamish points out that even in the latter case RYK was not consistent and quite arbitrary using his judgment where to introduce the Zoharic ideas.
Where I had the most difficulties is when I realized how much of an influence the Hemdas Yomim has on our daily praxis. Just a fast look in the index one can see that it is one of the most oft quoted sources. That is a very suspect book claimed by some to have been authored by the Shabbtai Tzvi prophet Natan of Gaza. How many of our practices are influenced by this Messianic disaster?
A fascinating chapter deals with eating fish on Shabbos. Tracing it from the Gemara Shabbos 118b through the Possekim, the famous Tur question to his father the Rosh whether he can make do with “Kassa D’eharsannah “(probably a dried cod called Bacalhau that is readily available cheaply in the Iberian Peninsula) because of his extreme poverty, and to the Shulchan Aruch who does not make it any mention of it. The reason given for eating fish on Shabbos is that it is part of the Mitzvah of Oneg Shabbos and therefore it is a matter of taste. One cannot legislate taste.
But then the story takes on a weird twist. Fish becomes important because supposedly Tzadikkim end up in fish after a transmigration of their souls (amazingly Aruch Hashulchan uses this reasoning quoting the Kitzur Hashelah) and by eating the soul containing fish, the Mitzvah elevates the soul of that Tzaddik. And of course Hemdas Yomim adds his two senses to the mix.
Here are the five reasons that develop over time:
The original rational one: Tastes good.
A symbolic one:
The fish’s eyes are always open a symbol of God’s providence that is constant.
Three superstitious ones:
By eating the fish in a meal that is a Mitzvah the soul that transmigrated in it is saved.
A kabalistic concept of elevating sparks. (?)
Another Kabalistic concept of Sefirotic connection. (?)
It may be a good idea to stop eating fish on Shabbos altogether. Too much voodoo!
There is much more in the book just on the fish topic alone. It is an all encompassing study well worth reading. It also makes you wonder how much external influences have entered our daily life. Maybe it is time to revert to pure Rambam legislation where all this superstition has not yet had an impact.
Other books on related topics:
Professor Ta Shema "Haniglah Shebanistar".
Professor Yakov Katz : Halacha Vekabalah"