Abstract: A block finder operates on one-dimensional digitized text, to group together those portions which are likely to contain related subjects matter, and to mark the grouped portions so that, at a later step of natural-language processing, only that block within which a word is found is searched for a related words or words. The block finder (210) extracts two-dimensional symbols, such as paragraph symbols (314), from the text, and stores the text in a grid of cells of a “two-dimensional” memory. All of the grid locations are classified as text (T) or space (white or W). Prefiltering (316) of the text deletes white spaces between sentences. Boundaries of the block are identified by examining each cell, and at least some of its adjoining cells, and identifying as an edge those boundaries between cells in which a transition between T and W occurs. This results in a list of unit-length boundary edges with top, bottom, left or right attributes.