pdf = Prawn::Document.new do
  text "The Prince", :align => :center, :size => 48
  text "Niccolò Machiavelli", :align => :center, :size => 20
  move_down 42

  column_box([0, cursor], :columns => 3, :width => bounds.width) do
  text((<<-END.gsub(/s+/, ' ') + "nn") * 20)
   All the States and Governments by which men are or ever have been ruled,
   have been and are either Republics or Princedoms. Princedoms are either
   hereditary, in which the bla bla bla bla .....
   END
  end
end.render

module Prawn
  class Document

    def reflow_column_box(*args, &block)
      init_column_box(block) do |parent_box|
        map_to_absolute!(args[0])
        @bounding_box = ReflowColumnBox.new(self, parent_box, *args)
      end
    end

    private

    class ReflowColumnBox < ColumnBox
      def move_past_bottom
        @current_column = (@current_column + 1) % @columns
        @document.y = @y
        if 0 == @current_column
          @y = @parent.absolute_top
          @document.start_new_page
        end
      end
    end
  end
end

column_box([0, cursor], :columns => 3, :width => bounds.width) do

reflow_column_box([0, cursor], :columns => 3, :width => bounds.width) do

require 'prawn'

text_to_write = ((<<-END.gsub(/s+/, ' ') + "nn") * 20)
 All the States and Governments by which men are or ever have been ruled,
 have been and are either Republics or Princedoms. Princedoms are either
 hereditary, in which the bla bla bla bla .....
 END

pdf = Prawn::Document.generate("test.pdf") do
  text "The Prince", :align => :center, :size => 48
  text "Niccolò Machiavelli", :align => :center, :size => 20
  move_down 42

  starting_y = cursor
  starting_page = page_number

  span(bounds.width / 3, position: :left) do
    text_to_write = text_box text_to_write, at: [bounds.left, 0], overflow: :truncate
  end

  go_to_page(starting_page)
  move_cursor_to(starting_y)

  span(bounds.width / 3, position: :center) do
    text_to_write = text_box text_to_write, at: [bounds.left, 0], overflow: :truncate
  end

  go_to_page(starting_page)
  move_cursor_to(starting_y)

  span(bounds.width / 3, position: :right) do
    text_box text_to_write, at: [bounds.left, 0]
  end
end

float do
        span((bounds.width / 3) - 20, :position => :left) do
                # Row Table Code
        end
end

float do
        span((bounds.width / 3) - 20, :position => :center) do
                # Row Table Code
        end
end

float do
        span((bounds.width / 3) - 20, :position => :right) do
                # Row Table Code
        end
end

column_box(reflow_margins: true, columns: 3)