Some care is needed in considering the problem of allusions. There may be worthy and unworthy motives behind their employment ad their enjoyment. There are some to whom a familiarity with literature occasions a sense of superiority over others which is trivial and mean. The pleasure of recognition, proportional as it is to the difficulty or unobtrusiveness of the allusion is a thing of slight value, not to be confused with literary or poetic values. It is perfectly possible for a reader, familiar with the _Nativity Hymn_, for example, to receive all that Shelley intended without ever noticing the allusion, without, that is to say, any recognition. But the erudite often forget that this happens. To turn the capacity of recognising recondite references into a shibboleth by which culture may be estimated is a perversion to which scholarly persons are too much addicted. The point is worth mentioning, since this snobbishness, percolating down (or, if the metaphor be preferred, by repercussion) is responsible for much insincerity and timidity, for wrong attitudes of many kinds towards literature, for irritation and oppression developing into distaste and neglect of poetry. Allusion is a trap for the writer almost as effective as for the academic critic. It invites insincerity. It may encourage and disguise laziness. When it becomes a habit it is a disease. But these dangers form no ground for denying to allusion, and the similar resources of which it is typical, a fit and justifiable place in poetry.