 In understanding how disability may be compatible with high levels of well-being, understood in objective terms, it is helpful to distinguish intrinsic from instrumental value. An activity may valuable for itself, e.g., seeing as a rich sensory experience; or instrumentally, for what it achieves or contributes to, e.g., seeing as a means of finding an object. As intuitive as the distinction seems, it is difficult to make clearly. First, there is deep disagreement about what is of ultimate value. Second, it is possible to parse many activities and conditions indefinitely into instrumentally valuable means and intrinsically valuable ends, e.g., making money or friends can be seen as an end in itself, or as a means to obtaining comfort and security (see  SEP entry on intrinsic vs. extrinsic value).