Phrase usually used is within the four corners of the document, which refers to the principle that the interpretation of a document should be derived primarily from the writing contained in the document and not from outside of the document (the four corners of the paper) that would provide extrinsic evidence. The actual written words of the contract should be examined first. The face of a written instrument. That which is contained on the face of a deed (without any aid from the knowledge of the circumstances under which it is made) is said to be within its four corners, because every deed is still supposed to be written on one entire skin, and so to have but four corners. To look at the four corners of an instrument is to examine the whole of it, so as to construe it as a whole, without reference to any one part more than another. 2 Smith, Lead. Cas, 295.