I need to analyze and explain this quote in a 400+ word essay, any

i need to analyze and explain this quote in a 400+ word essay, any tips would be super useful. and if anyone wants to do it for me, i wouldn’t mind hahaha. but i do need help… alot of help!!

Principles of Human Knowledge (section 22)
“I am afraid I have given you cause to think me needlessly long-winded in handling this subject. For what is the point of hammering away at something that can be proved in a line or two, convincing anyone who is capable of the least reflection? Look into your own thoughts, and try to conceive it possible for a sound or shape or motion or color to exist outside the mind, or unperceived. Can you do it? This simple thought-experiment may make you see that what you have been defending is a downright contradiction. I am willing to stake my whole position on this: if you can so much as conceive it possible for one extended movable substance—or in general for any one idea or anything like an idea—to exist otherwise than in a mind perceiving it, I shall cheerfully give up my opposition to matter; and as for all that great apparatus of external bodies that you argue for, I shall admit its existence, even though you cannot either give me any reason why you believe it exists, or assign any use to it when it is supposed to exist. I repeat: the bare possibility of your being right will count as an argument that you are right.”