Usages
3 distinct jobs 以 does in the Analects, each with examples from the text.
1Preposition (with, by means of)
The most common use - indicates the instrument or means by which something is done, like modern 用.
子曰：「為政以德，譬如北辰，居其所而眾星共之。」
The Master said: "He who exercises government by means of his virtue may be compared to the north polar star, which keeps its place and all the stars turn towards it."
Legge 1861
以 = by means of, with
子曰：「君子博學於文，約之以禮，亦可以弗畔矣夫！」
The Master said: "The superior man, extensively studying all learning, and keeping himself under the restraint of the rules of propriety, may thus likewise not overstep what is right."
Legge 1861
The bare instrumental shape.
子曰：「能以禮讓為國乎？何有？不能以禮讓為國，如禮何？」
The Master said: "If a prince is able to govern his kingdom with the complaisance proper to the rules of propriety, what difficulty will he have? If he cannot govern it with that complaisance, what has he to do with the rules of propriety?"
Legge 1861
以 gives the means, 為 the thing done.
子曰：「道之以政，齊之以刑，民免而無恥；道之以德，齊之以禮，有恥且格。」
The Master said: "If the people be led by laws, and uniformity sought to be given them by punishments, they will try to avoid the punishment, but have no sense of shame. If they be led by virtue, and uniformity sought to be given them by the rules of propriety, they will have the sense of shame, and moreover will become good."
Legge 1861
以 = with, using
2Conjunction (in order to)
Links two clauses where the second expresses purpose or result: "in order to" or "thereby."
子曰：「志士仁人，無求生以害仁，有殺身以成仁。」
The Master said: "The determined scholar and the man of virtue will not seek to live at the expense of injuring their virtue. They will even sacrifice their lives to preserve their virtue complete."
Legge 1861
以 points forward to the purpose.
子曰：「志士仁人，無求生以害仁，有殺身以成仁。」
The Master said: "The determined scholar and the man of virtue will not seek to live at the expense of injuring their virtue. They will even sacrifice their lives to preserve their virtue complete."
Legge 1861
The negative half of the same line.
子謂子貢曰：「女與回也孰愈？」對曰：「賜也何敢望回。回也聞一以知十，賜也聞一以知二。」子曰：「弗如也！吾與女弗如也。」
The Master said to Zigong: "Which do you consider superior, yourself or Hui?" Zigong replied: "How dare I compare myself with Hui? Hui hears one point and knows all about a subject; I hear one point, and know a second." The Master said: "You are not equal to him. I grant you, you are not equal to him."
Legge 1861
以 = thereby, as a result
子曰：「弟子入則孝，出則弟，謹而信，汎愛眾，而親仁。行有餘力，則以學文。」
The Master said: "A youth, when at home, should be filial, and, abroad, respectful to his elders. He should be earnest and truthful. He should overflow in love to all, and cultivate the friendship of the good. When he has time and opportunity, after the performance of these things, he should employ them in polite studies."
Legge 1861
以 = in order to
3Take as (以...為)
The set construction 以A為B means "to take A as B" or "to consider A to be B."
子夏問曰：「『巧笑倩兮，美目盼兮，素以為絢兮。』何謂也？」子曰：「繪事後素。」曰：「禮後乎？」子曰：「起予者商也！始可與言詩已矣。」
Zixia asked, saying: "What is the meaning of the passage — 'The pretty dimples of her artful smile! The well-defined black and white of her eye! The plain ground for the colors?'" The Master said: "The business of laying on the colors follows the preparation of the plain ground." "Ceremonies then are a subsequent thing?" The Master said: "It is Shang who can bring out my meaning. Now I can begin to talk about the odes with him."
Legge 1861
以為 = take as, serves as
曾子曰：「士不可以不弘毅，任重而道遠。仁以為己任，不亦重乎？死而後已，不亦遠乎？」
The philosopher Zeng said: "The officer may not be without breadth of mind and vigorous endurance. His burden is heavy and his course is long. Perfect virtue is the burden which he considers it is his to sustain; — is it not heavy? Only with death does his course stop; — is it not long?"
Legge 1861
The object is fronted before 以.
子夏問孝。子曰：「色難。有事弟子服其勞，有酒食先生饌，曾是以為孝乎？」
Zixia asked what filial piety was. The Master said: "The difficulty is with the countenance. If, when their elders have any troublesome affairs, the young take the toil of them, and if, when the young have wine and food, they set them before their elders, is THIS to be considered filial piety?"
Legge 1861
以為 = to consider as, to take as
Combos
9 fixed patterns built on 以, with the role each plays and where to read them.
"How?" / "By what means?" / "Why?"
Asks about the reason, method, or means. 以 serves as "by means of."
"Therefore" / "For this reason"
是 (this) + 以 (by means of) = "by means of this" → "therefore."
"The reason why..." / "That by which..."
Can mean either "the reason" or "the means by which." Context determines meaning.
"To consider as..." / "To think that..."
Very common pattern: "take X as Y" or "think X is Y."
"Can" / "May" / "Is possible to"
Auxiliary indicating permission or ability.
"Can serve as..." / "Can be considered..."
Extended form of 可以 with specific role or function.
"Cannot" / "Is not possible to"
Extended form of 不可.
"Have no means to..." / "Cannot..."
Indicates lack of means or method.
"…them by means of…" — verb + object pronoun + instrument
A verb takes 之 as its object, then 以 introduces what it is done with. 2.3 sets four of these in parallel to contrast governing by law with governing by virtue.