This section is from the book "The Law Of Contracts", by William Herbert Page. Also available from Amazon: Commercial Contracts: A Practical Guide to Deals, Contracts, Agreements and Promises.
If one reads the contract, or has it read to him, and misinterprets its meaning, he is bound thereby if the contract is unambiguous and if the adversary party does not know of such mistake,1 even if parties do not understand their rights under the contract.2 If the parties know and intend the words which they use, the fact that they mistake the legal effect of the contract does not amount to mistake so as to make a defense at law.3 If a written offer is explained correctly to the offeree, he can not avoid the contract made by the acceptance of such offer on the ground that he did not understand the terms of the offer.4 A misunderstanding by one party of a term which, by the usage of the trade, had a definite meaning,5 does not render the contract void. If a borrower signs a note which provides for the payment of the principal and interest together in installments, believing that the principal bears interest at seven per cent, per annum, whereas by reason of payment in installments it actually bears interest at nearly twelve per cent, per annum, but the lender is not guilty of fraud or misrepresentation, such contract is valid.6
Mistake as to the legal effect of the instrument has, however, been regarded as a ground for denying specific performance. If an instrument is read correctly to one who is unable to read because he is without his glasses, and both the person who reads the instrutation, or that any deception was practiced by misreading it to him. His inability to read English or to understand the contents of the paper is no excuse. This was his own negligence. He could and should have sought the assistance of some one capable of properly informing him. * * * It can not be tolerated that a man shall execute a written instrument and when called upon to abide by its terms, say, merely, that he did not read it or know what it contained": Albrecht v. Ry., 87 Wis. 105, 109, 41 Am. St. Rep. 30, 58 N. W. 72 [citing Fuller v. Ins. Co., 36 Wis. 599; Sanger v. Dun, 47 Wis. 615, 32 Am. Rep. 789, 3 N. W. 388; Sheanon v. Ins. Co., 83 Wis. 507, 53 N. W. 878; Upton v. Tribilcock, 91 U. S. 45, 23 L. ed. 203]. 1 United States. American Fine Art Co. v. Simon, 140 Fed. 529.
Illinois. Carter v. Love, 206 111. 310, 69 N. E. 85.
Louisiana. Maginnis v. Oir Co., 47 La. Ann. 1489, 18 So. 459.
Massachusetts. Wheaton Building and Lumber Co. v. Boston, 204 Mass. 218, 90 N. E. 598.
North Carolina. Leonard v. Southern Power Co., 155 N. Car. 10, 70 S. E. 1061.
2 Soley v. Jones, 208 Mass. 561, 95 N. E. 94; Atlas Shoe Co. v. Bloom, 209 Mass. 563, 95 N. E. 952.
3 First Natl. Bank v. Shank, 53 Cola 446, 128 Ac. 56.
4 Bibelhausen v. Bibelhausen, 159 Wis. 365, 150 N. W. 516.
5 Soper v. Tyler, 77 Conn. 104, 58 Atl. 699.
6 Equitable Savings & Loan Association v. Barnes, 69 Wash. 1, 124 Ac. 118; Equitable Savings & Loan Assn. v. Bowes, 70 Wash. 169, 126 Ac., 436.