The courts of Ḥíra and Ghassán were well known to the wandering minstrels of the time before Muḥammad, who flocked thither in eager search of patronage and remuneration. We may be sure that men like Nábigha, Labíd, and A‘shá did not remain unaffected by the culture around them, even if it seldom entered very deeply into their lives. That considerable traces of religious feeling are to be found in Pre-islamic poetry admits of no denial, but the passages in question were formerly explained as due to interpolation. This view no longer prevails. Thanks mainly to the arguments of Von Kremer, Sir Charles Lyall, and Wellhausen, it has come to be recognised (1) that in many cases the above-mentioned religious feeling is not Islamic in tone; (2) that the passages in which it occurs are not of Islamic origin; and (3) that it is the natural and necessary result of the widely spread, though on the whole superficial, influence of Judaism, and especially of Christianity.[269] It shows itself not only in frequent allusions, _e.g._, to the monk in his solitary cell, whose lamp serves to light belated travellers on their way, and in more significant references, such as that of Zuhayr already quoted, to the Heavenly Book in which evil actions are enscrolled for the Day of Reckoning, but also in the tendency to moralise, to look within, to meditate on death, and to value the life of the individual rather than the continued existence of the family. These things are not characteristic of old Arabian poetry, but the fact that they do appear at times is quite in accord with the other facts which have been stated, and justifies the conclusion that during the sixth century religion and culture were imperceptibly extending their sphere of influence in Arabia, leavening the pagan masses, and gradually preparing the way for Islam. CHAPTER IV THE PROPHET AND THE KORAN With the appearance of Muḥammad the almost impenetrable veil thrown over the preceding age is suddenly lifted and we find ourselves on the solid ground of historical tradition. In order that the reasons for this change may be understood, it is necessary to give some account of the principal sources from which our knowledge of the Prophet's life and teaching is derived. [Sidenote: Sources of information: I. The Koran.] [Sidenote: How it was preserved.] [Sidenote: Value of the Koran as an authority.]