A text display system provides a restricted copy-and-paste operation such that only a limited percentage less than 100% of a source text can be copied. The strategy assumes that a document contains a plurality of words and sentences that a restriction can be placed upon. While it is possible to highlight any amount of text via a typical select function (e.g., mouse drag over text), depending on the number of words at the sentence, paragraph or document level, the present invention limits how much of the selected text can be copied. The system provides the user with instant feedback via visual, tactile or other means, when a selection exceeds the system-imposed limit. The restriction permits the copy-and-paste operation of key ideas from the source text, potentially for further elaboration upon in future writing, and yet discourages indiscriminant copying leading to plagiarism.