To express great numbers the most useful similes are drawn from stars, pearly drops of dew, and, most frequently, leaves in autumn.[108] An exceedingly popular simile is that of the oak and ivy, or the elm and the vine.[109] Its use is obvious. The rising and the setting sun represent various forms of prosperity and adversity.[110] From Waller on, the Milky Way typifies virtues so numerous that they shine in one undistinguished blaze.[111] A large class of similitudes is drawn from water in some form. In this respect Dryden is typical. It is surprising to observe how many of his metaphors and similes are based on seas, streams, and storms,[112] and his most excellent use of Nature is in these similitudes, though after going over many of them one comes to feel that they are all made upon much the same pattern. After Dryden conventional comparisons based on floods and angry seas are frequent. The customary form of the river simile of this period is the comparison of some man’s character, or actions, or literary style to some historic rivers with marked features. Prior uses the rapid Volga to represent the impetuous “young Muscovite,” while he compares his own king to the gentle Thames;[113] and he compares the Romans to the Tyber.[114] Pope scornfully likens Curll to the Uridanus.[115] Cowley compares Jonathan to the fair Jordan.[116] Halifax compares the reign of Charles II to the Thames.[117] Armstrong wishes his own style to combine the qualities of the Tweed and the Severn.[118] Hughes likened his Muse to the wanton Thames.[119] Roscommon thought a dull style was like the passive Soane.[120] Somerville compared Allan Ramsay’s poetry to Avona’s silver tide.[121] Thomson said that De La Cour’s numbers went gliding along in “trickling cadence” and were like the flow of the Euphrates.[122] Chief among similes of this sort is Denham’s well-known apostrophe to the Thames.[123] There is also frequent use of rivers in a more general way, as when Parnell compares the strains of the Psalmist to a rolling river,[124] and Stanhope compares Pope’s style to a gliding river,[125] and Addison compares Milton’s poems to a clean current showing an odious bottom,[126] and Dryden compares Sir Robert Howard’s style to a mighty river.[127] The use of a river as a simile for life is not infrequent. For various purposes the Nile was often used. Its annual overflow and its unknown fountain-head are the chief characteristics drawn upon. The river similes seem as a whole to be more effectively worked out and more gracefully managed than most of the other similes of the period, although they have in no case the beauty and profound symbolism characteristic of the river similes of Wordsworth, Matthew Arnold, and Lowell. Another common form of comparison is that in which the seasons or the various aspects of the day are used to describe some person. One of the happiest examples is from Marvell.