discuss swifts satire on the human desire for immortality

I think your question refers to the immortal Struldbrugs in Voyage Three. Really Swift asks if we would actually like to live forever. Swift regards immortality as a sort of "living death." The Struldbrugs are depressed, perhaps because there is no reason to act quickly. They have all the time in the world. Meanwhile, they have plenty of time to see what mortals have done for themselves and their society in their fleeting time alive.