Yield runs a block, but I don't understand what block this yield is running. And more! Come on in if you like to teach!

I understand that "yield" runs a "block" of code sharing the same name as the method containing "yield." However, in this particular code (which allows you to write a speech in lines and then print to the screen) I don't understand what the "def each" method is doing on lines 26-28.

Can someone explain this in detail? And I mean slow: as if I have brain damage. I know this method is making it possible to print each line consecutively, but I have absolutely no clue about how it's doing that.

Relevant questions (mostly center on lines 26-28 near the bottom, the def each method):

• why is there &block? I don't see a block.call anywhere? (line 26)
• isn't .each already defined by default in Ruby? Did we redefine it? (lines 26-28)
• how do the pipes || work? Why did we have to put "line" in the pipes? (lines 26-28)
• how is yield working properly here if we didn't create a separate block that shares the name of this method? I thought that's how yield worked: it ran the code from a block that shares the name of method yield is in. (lines 26-28)
• shouldn't it be for each line we "puts" that line rather than yield it? Why did we write the code that prints the speech to the screen down on lines 36-38 instead of including it here?

And finally the code itself:

class Speech
    def initialize 
        print "What is the speech name? "
        @title = gets.chomp 
        @lines = []
        while add_line
            puts "Line added."
        end
    end

    def title 
        @title
    end

    def add_line
        puts "Add a line: (blank line to exit)"
        line = gets.chomp
        if line.length > 0
            @lines.push line 
            return line
        else
            return nil
        end
    end

    def each(&block)
        @lines.each { |line| yield line}
    end

 end


 speech = Speech.new
 puts "#{speech.title.upcase}\n\n"

 speech.each do |line|
    puts "#{line}"
 end

Hopefully there are some natural teachers out here in the forum that love answering questions--I'm certainly full of them! :)