Topic one of peculiar difficulty, sec 171. Embarrassed by ambiguity of terms, sec 172. Also by confusion of classification, sec 173. Will and expression must coincide, sec 174.

II. Conscious Error

Promises known to be in jest do not bind, sec 175.

Error when conscious, exposes to rescission and action for deceit, sec 176.

III. Unconscious Error Of Apprehension

In Roman law unconscious essential error prevents inception of contract, sec 177. In our own law this view obtains, sec 178. Error to be distinguished from impossibility of performance, sec 179. Essential error as to parties precludes contract, sec 180. And so as to error as to subject matter, sec 181. No title passes when only bare charge is given, sec 182. No title passes in false personation, sec 183. Contract must be made with party suing, sec 184. Signature to wrong document does not bind, sec 185.

Essential error as to identity of thing precludes contract, sec 186.

And so as to error as to generic character of property, sec 187.

"Substantial" error does not necessarily have this effect, sec 188.

Nor does error as to quality, sec 189.

Error as to quantity or price only pro tanto invalidates, sec 190.

If there be fraud as to quantity or quality, defrauded party may hold to bargain and sue for damages, sec 191.

Error in accounts, and as to price, may be corrected pro tanto, sec 192.

Error in motive not essential, sec 193.

Error as to collateral or future matters not essential, sec 194.

Contracts of bailment subject to same rules, sec 195.

Negligent error does not excuse, sec 196.

Money paid under mistake may be recovered back, sec 197.

Error in law does not avoid, sec 198.

Error in subsumption of facts not one of law, sec 199.

Special knowledge not presumed in non-specialist, sec 200.

Error of law, when acted on fraudulently, avoids, sec 201.

IV. Error Of Expression

Error of expression unessential, sec 202. Party is estopped from denying that his expressions were correct, sec 202 a. Error in time may be corrected, sec 203. Patent error cannot be corrected by extrinsic proof, sec 204.

V. Rectification

Bilateral error maybe corrected, sec 205.

Concurrent error ground for rectification, sec 206.

Rescission granted on proof of unilateral mistake; rectification on proof of bilateral, sec 207.

Proof should be strong and plain, sec 208. Contract requiring distinct modes of proof cannot be inserted, sec 209. Obvious mistake may be corrected by context, sec 210. Rectification not granted against bona fide purchaser, sec 211.