そのものだ how is it translated?

Question

So, I recently was reading something and I found the structure そのものだ, which at first glance it is not quite mean "that thing" as I thought, and the best explanation of it that I could find was in the "A dictionary of Advanced Japanese grammar", and from what I saw, after a noun, it is translated as "itself" or "the picture of/the embodiment of~ (health, beauty etc.)
The book said that after a Na-adjective such as in the examples taken from the book

温厚そのものだ (s.o is very gentle)
温厚そのものの人柄 (a very gentle personality)

In these examples, 'sono mono' is just used to place more emphasis? (If you could provide me with more examples it would be great, because most of the ones that are in the book and what I saw on websites, they are usually translated with the meanings itself" or "the picture of/the embodiment of~ like I mentioned.
My sentence was like this:

さくらが捨てた感傷そのものだ

(someone is narrating and holding an object that belonged to Sakura, which the narrator knew she was attached to it, but after a painful event, Sakura abandoned it, a metaphor for throwing away her sentimentality)
and I think here it could translate as:

"Sakura threw (this-the item) the very embodiment of her sentimentality"

I hope I could explain well enough!

Answer 1

～そのもの is an emphatic expression that can be translated in various ways, including "～ itself", "the very ～", "exactly ～", "typical ～", "perfectly", "by/in itself", "nothing but ～", "embodiment of ～" and so on.

(それは)さくらが捨てた感傷そのものだ。
This item is the very (symbol of the) sentimental feeling Sakura has thrown away.

Note that the subject of this sentence is not Sakura but the "item" itself. さくらが捨てた is a relative clause that modifies 感傷そのもの. As you said, this is a metaphorical sentence similar to "You are my sunshine" or "This is a cornerstone".