Amendment 25, sections 3 and 4 are confusing?

Question

Could someone explain each sentence to me throughly please?

And thanks.

Answer 1

Amendment 25 allows for the VP to take over the president's job if the president is incapacitated, either temporarily or permanently.

Well if this is possible, the first question is: Who decides if the president is incapacitated? I mean if the VP could just decide by himself, many VPs would have just taken over the office.

So Section 3 explains that the president himself may decide he's  unable to do his job.  In that case he sends a letter to the leaders of both houses of Congress, the Speaker of the House and the President Pro Tempore of the Senate.  And the president can also decide when he is able to do his job again and send another letter to these people cancelling the order.

Section 4 is for when the president doesn't declare himself incapacitated.  In this case the VP and a majority of the cabinet ('principle officers of the executive departments'--that's the cabinet) must decide the president is incapacitated for him to be removed from office against his will.

If the president has been removed from his job by Section 4 (i.e. against his will), then it takes the VP and another majority of cabinet officers to agree to reinstate him.  The amendment allows Congress to change this reinstatement provision to add some other group of people, perhaps congressional leaders.