A far more difficult collection, consisting of fifty-two stanzas, occurs in the first book (164). Nothing here is directly described, the language being always symbolical and mystical. The allusions in several cases are so obscurely expressed that it is now impossible to divine the meaning. Sometimes the riddle is put in the form of a question, and in one case the answer itself is also given. Occasionally the poet propounds a riddle of which he himself evidently does not know the solution. In general these problems are stated as enigmas. The subject of about one-fourth of them is the sun. Six or seven deal with clouds, lightning, and the production of rain; three or four with Agni and his various forms; about the same number with the year and its divisions; two with the origin of the world and the One Being. The dawn, heaven and earth, the metres, speech, and some other subjects which can hardly even be conjectured, are dealt with in one or two stanzas respectively. One of the more clearly expressed of these enigmas is the following, which treats of the wheel of the year with its twelve months and three hundred and sixty days:-- Provided with twelve spokes and undecaying, The wheel of order rolls around the heavens; Within it stand, O Agni, joined in couples, Together seven hundred sons and twenty. The thirteenth or intercalary month, contrasted with the twelve others conceived as pairs, is thus darkly alluded to: "Of the co-born they call the seventh single-born; sages call the six twin pairs god-born." The latter expression probably alludes to the intercalary month being an artificial creation of man. In the later Vedic age it became a practice to propound such enigmas, called "theological problems" (brahmodya), in contests for intellectual pre-eminence when kings instituted great sacrifices or Brahmans were otherwise assembled together.