Shakespeare's Sonnets: Thus can my love excuse the slow offence

Thus can my love excuse the slow offenceOf my dull bearer, when from thee I speed.From where thou art, why should I haste me thence?Till I return, of posting is no need.O what excuse will my poor beast then findWhen swift extremity can seem but slow?Then should I spur, though mounted on the wind,In wingèd speed no motion shall I know;Then can no horse with my desire keep pace,Therefore desire (of perfect'st love being made)Shall neigh no dull flesh in his fiery race,But love, for love, thus shall excuse my jade, Since from thee going he went wilful slow, Towards thee I'll run and give him leave to go.