Answer:
The comparison was made to show how cities are dependent on farms and that is why it is necessary to stimulate the work of farmers.
Step-by-step explanation:
Bryan's speech was made to encourage a measure that would help farmers to carry out their duties. This measure sought to stimulate the minting of silver to gold in 16 to 1, which would increase the circulation of money and allow an increase in credit for agricultural production.
Bryan knew that this measure would be controversial, especially in large cities that they thought would be harmed. To debate this thought Bryan said: "Burn down your cities and leave our farms, and your cities will spring up again as if by magic. But destroy our farms and the grass will grow in the streets of every city in the country." By this he meant that it was the obligation of the cities to support the work of the farms, because the cities are dependent on the farms, but the farms are not dependent on the cities.