Hexagram 49, Gé (Revolution): Line 4
革卦九四 · 泽火革 · 中文版
九四：悔亡，有孚改命，吉。
The line (Legge)
The fourth NINE, undivided, shows occasion for repentance disappearing (from its subject). Let him be believed in; and though he change (existing) ordinances, there will be good fortune.
Small Image commentary
'The good fortune consequent on changing (existing) ordinances' is due to the faith reposed in his aims.
象曰：改命之吉，信志也。
In plain words
Regret vanishes; with sincerity, changing the mandate brings good fortune. The fourth line is yang in a yin place and has entered the upper trigram: the time for change has come. Founded on sincerity, it changes the old mandate; the Chinese word for revolution comes from this hexagram. The Small Image says changing the mandate is fortunate because its aims are trusted.
Applying it to your situation
If you are about to make a major change, this line suggests first making sure people believe in your good faith. Why would people trust you?
Position
A solid (yang) line in the fourth place, which is a yin (even) place, so it is not in its proper place. Its partner is line 1; both are yang, so they do not respond.
If this line moves
With this line moving alone, Gé changes into Hexagram 63 Jì Jì (After Completion). The Jiaoshi Yilin verse for this change (Chinese): 焦氏易林·革之既济.
A recorded case from Takashima
Ge to Ji Ji: bad luck going, good luck coming: A friend asked about his fortunes and received the fourth line of Ge, "regret vanishes; with trust, changing the mandate brings good fortune". Takashima called it the hexagram of casting off the old: past troubles were over, and from now on he should change course, since carrying on as before would not pay. He explained "changing the mandate" with five-year cycles of fortune and the earth element.
The hexagram
Hexagram 49 Gé (Revolution). The Judgment: (What takes place as indicated by) Ge is believed in only after it has been accomplished. There will be great progress and success. Advantage will come from being firm and correct. (In that case) occasion for repentance will disappear.
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English text: James Legge, The Yi King (Sacred Books of the East, vol. 16, 1882), public domain, as transcribed by the Chinese Text Project. Chinese: the received text. Offered for study and reflection, not as prediction. Plain-English readings and position notes by this site.