A philosophical investigation of certain basic concepts in mathematics (e.g., "number"), physics (e.g., "space"), and biology (e.g., "life"). A clarified understanding of these concepts will be applied to answering such questions as: Does a finite universe have an end? Can there be empty space (a void)? Do "imaginary" numbers qualify as numbers? Is life reducible to physical-chemical interactions? Is evolution a hypothesis or an established fact?