The church is mentioned for the first time in the earlier half of the eighth century as a chapel ([Greek: euktêrion]) which Thekla, the eldest daughter of the Emperor Theophilus, restored and attached to her residence at Blachernae.[341] The princess was an invalid, and doubtless retired to this part of the city for the sake of its mild climate. To dedicate the chapel to her patron saint was only natural. As already intimated, the church was rebuilt from the foundations, in the eleventh century, by Isaac Comnenus, in devout gratitude for his escape from imminent death[342] in the course of his campaign against the barbarous tribes beside the Danube, when he was overtaken at the foot of the Lovitz mountain by a furious tempest of rain and snow. The plain on which his army was encamped soon became a sheet of water, and many of his men and animals were drowned or frozen to death. Thunder, lightning, and hurricane combined to produce an awful scene, and there were moments when the whole world seemed on fire. The emperor took shelter under a large oak, but, fearing the tree might be thrown down by the furious wind, he soon made for open ground. Scarcely had he done so when the oak was torn up by the roots and hurled to the earth. A few moments later the emperor would have been killed. This narrow escape occurred on the 24th September, the festival day of S. Thekla, and, therefore, attributing his deliverance to her intervention, Isaac rebuilt and greatly beautified the old sanctuary dedicated to her in Blachernae, and frequently attended services there in her honour. Anna Comnena[343] speaks of the restored church in the highest terms. According to her it was built at great cost, displayed rare art, and was in every way worthy of the occasion which led to its erection. Zonaras[344] is not so complimentary. He describes the church as a monument of the niggardliness of Isaac Comnenus. In any case, it was pulled down and rebuilt in the following century by the Emperor John Comnenus in splendid style, and dedicated to the Saviour.[345] As the beauty and wealth of a Byzantine sanctuary were exhibited in the lavish adornment of the interior, it is possible that the church of S. Thekla, though small and outwardly plain, may have been a beautiful and rich building in its latest Christian character. It had then the honour of seeing among the worshippers before its altar Anna Dalassena, the mother of the Comneni. For, when charged with the government of the Empire during the absence of Alexius Comnenus from the capital, that able woman came often to pray in this church, 'lest she should be immersed in merely secular affairs.'[346] _Architectural Features_ (For Plan see p. 206)