I asked: If Tom believes that snow is white, and Carol believes that snow is white, are they believing the same thing or not? And Anthony asked rhetorically, if I am eating a hamburger, and you are eating a hamburger, are we both eating the same thing or not? If I am nervous, and you are nervous, are we both experiencing the same emotion? If I have 5 apples, and you have 5 apples, do we both have the same number of apples? I'm reading a copy of "The Great Gatsby". You're reading a different copy of "The Great Gatsby". Are we both reading the same thing?
If we are both eating a hamburger, then in one sense we are eating the same thing, namely hamburger. Perhaps we could say the sameness in question is a 'formal' identity. In another sense we are not, given that there are probably two hamburgers in question, hence there is no sameness in the sense of 'numerical' identity. Clearly there is no numerical identity between what Tom and Carol believe, even though they both believe that snow is white. But if the identity is formal, where is the matter which has the form? The form of hamburger is embedded an organic carbon compound (meat). The form of "The Great Gatsby" is embedded in another compound (tree pulp, paper). What is the material that embeds the form of the proposition 'snow is white'?