不患人之不己知 患不知人也?

These days I am studying Chinese writing (漢文) by doing self study with a Korean book ("한문해석법"), which is not easy without an instructor. The book explains many things, but, of course, I still have questions. For example, I have a question about the following sentence, which comes from the section in the book explaining negative commands:

不患人之不己知 患不知人也 (불환인지불기지 환불지인야)

Don't worry that people will not recognize you; worry that you will not recognize people.

As you may know, Chinese sentences use a different word order from Korean. In fact, they supposedly use an English word order, that is, "subject-verb-object," but there are still some differences I do not yet understand. For example, I do not understand why the first part of the above Chinese sentence is written as it is.

Notice that the above Chinese sentence is actually made up of two sentences (clauses).

不患人之不己知 - Don't worry that people will not recognize you;

患不知人也 - worry that you will not recognize people.

I understand the second sentence because it follows the word order I would expect, but the first sentence has a different word order, for some reason. Here is the breakdown of the second sentence:

Worry (患) [you] do not (不) recognize (知) people (人) 也*

*也 acts like a period.

Notice that the above sentence has basically the same word order as a command in English, which makes sense to me. In other words, the object (people) comes after the verb (recognize). Now look at the word order of the first sentence, which does not make sense to me:

Do not (不) worry (患) that people (人之) do not (不) you (己) recognize (知);

Notice in the above sentence that the object (you) comes before the verb (recognize). Why? Was it a misprint?

다 같지 않다 vs. 다 같은 것은 아니다?

Notice the difference between the following two sentences:

1. 다 같지 않다. (None are the same. / No two are alike.)
2. 다 같은 것은 아니다. (Not all are the same. / Many are the same, but some are different.)

Sentence 1 refers to everything, but sentence 2 refers to only some.

These patterns can be used in other situations as well. Consider the following:

1. 항상 있지 않다. (There is never any. / ... is never [here].)
2. 항상 있는 것이 아니다. (Sometimes there is not any. / ... is not always [here.])
   -
3. 반듯이 되지 않는다. (It never works.)
4. 반듯이 되는 것은 아니다. (Sometimes it does not work.)

Notice the subtle differences? Now here is how you would write the above sentences in Chinese:

• 皆不同(개불동) - None are the same.
• 不皆同(불개동) - Not all are the same
  -
• 常不有(상불유) - There is never any.
• 不常有(불상유) - Sometimes there is not any.
  -
• 必不成(필불성) - It never works.
• 不必成(불필성) - Sometimes it does not work.

Notice that the only difference between the two Chinese expressions in each group is the order in which the characters appear.