Kittridge goes into more detail about the use of shadow and couplet within the initial couplet. "Shadow is the silhouette formed by a body that intercepts the sun's rays; a picture, reflection, or symbol. "Tend" means attend, follow as a servant, and is strictly appropriate to 'shadow' only in the first sense, though shadows is used here in the second… All men have one shadow each in the first sense; you being only one can yet cast many shadows, in the second sense, for everything good or beautiful is either a representation of you or a symbol of your merits," (Sonnets, p. 142). This definition helps elaborate on Shakespeare's extended metaphor and wordplay, explaining that shadow is that which is not palpable as well as the reflection of the young man in all that is real.