The idea of agreement involves community of intention.1 If the parties know that they intend different things, no agreement is reached. What are the consequences of mistake by which the parties intend different things while they believe that they intend the same thing Shall we take the actual intention of the parties and say that no contract has been entered into or shall we ignore the intention of the individual and substitute therefor the intention which the ordinary man would have had when he thus expressed himself The question is one which is discussed later in detail and which can not be summarized here.

1 For a definition of agreement, see Carter v. Prairie Oil & Gas Co., (Okla.), 160 Ac. 319.

For a discussion of the nature of agreement, see Tucker v. Pete Sheeran, Bro. & Co., 155 Ky. 670, 160 S. W. 176.

2 "A 'contract' is an agreement between two or more parties for the doing or not doing of some specified thing. There is no difference between a 'contract' and an 'agreement'": Douglass v. W. L. Williams Art Co., 143 Ga. 846, 85 S. E. 993. "We are unable to distinguish the difference between a contract and an agreement": Michael v. Kennedy, 166 Mo. App. 462, 148 S. W. 983.

1 "An agreement- is nothing more than 'a coming together of parties in opinion or determination; the union of two or more minds in a thing done or to be done; a mutual assent to do a thing' * *": Carter v. Prairie Oil & Gas Co. (Okla.), 160 Ac. 319 [citing Bouvier's Law Dictionary].

See Collective Acts as Distinguished from Contracts, by Leon Duguit, 27 Yale Law Journal, 753.