In 1844, he discovered the world's oldest and most complete Bible dated to around the mid-4th century and called Codex Sinaiticus after Saint Catherine's Monastery at Mount Sinai.

[1] While a student gaining his academic degree in the 1840s, he earned international recognition when he deciphered the Codex Ephraemi Rescriptus, a 5th-century Greek manuscript of the New Testament.

Winer's influence gave him the desire to use the oldest manuscripts in order to compile the text of the New Testament as close to the original as possible.

[3] Despite his father's death in 1835 and his mother's just a year later, he was still able to achieve his doctorate in 1838,[2] before accepting a tutoring job in the home of Reverend Ferdinand Leberecht Zehme in Grossstadeln where he met and fell in love with the clergyman's daughter Angelika.

[2] After a journey through southern Germany and Switzerland, and a visit to Strassburg, he returned to Leipzig to begin work on a critical study of the New Testament text.

[4] From October 1840 until January 1843 he was in Paris, busy with the treasures of the Bibliothèque Nationale, eking out his scanty means by making collations for other scholars, and producing for the publisher, Firmin Didot, several editions of the Greek New Testament, one of them exhibiting the form of the text corresponding most closely to the Vulgate.

His success in dealing with a manuscript that, having been over-written with other works of Ephrem the Syrian, had been mostly illegible to earlier collators, made him more well known, and gained support for more extended critical expeditions.

[4] In 1844 Tischendorf travelled the first time to Saint Catherine's Monastery at the foot of Mount Sinai in Egypt, where he found a portion of what would later be hailed as the oldest complete known New Testament.

He donated those 43 pages to King Frederick Augustus II of Saxony (reigned 1836–1854), to honour him and to recognise his patronage as the funder of Tischendorf's journey.

[8][9] Tischendorf reported in his 1865 book Wann Wurden Unsere Evangelen Verfasst, translated to English in 1866 as When Were Our Gospels Written in the section "The Discovery of the Sinaitic Manuscript" that he found, in a trash basket, forty-three sheets of parchment of an ancient copy of the Greek Old Testament, reporting that the monks were using the trash to start fires.

He returned a third time in January 1859 under the patronage of Tsar Alexander II of Russia with the active aid of the Russian government to find more of the Codex Frederico-Augustanus or similar ancient Biblical texts.

Indeed, he was never rich, but he staunchly defended the rights of the monks at Saint Catherine's Monastery when he persuaded them eventually to send the manuscript to the Tsar.

Thought lost since the Russian revolution, the document (Schenkungsurkunde) has now resurfaced in St Petersburg 2003, and has also been long before commented upon by other scholars like Kurt Aland.

[12] When the 4-volume luxury edition of the Sinai Bible was completed in 1862, C. Tischendorf presented the original ancient manuscript to Emperor Alexander II.

In 1859, he was named professor ordinarius of theology and of Biblical paleography, this latter professorship being specially created for him; and another book of travel, Aus dem heiligen Lande, appeared in 1862.

[16] Throughout his life Tischendorf sought old biblical manuscripts, as he saw it as his task to give theology a Greek New Testament which was based on the oldest possible scriptures.

The great edition, of which the text and apparatus appeared in 1869 and 1872, was called by himself editio viii; but this number is raised to twenty or twenty-one, if mere reprints from stereotype plates and the minor editions of his great critical texts are included; posthumous prints bring the total to forty-one.

The readings of the Vatican manuscript were given with more exactness and certainty than had been possible in the earlier editions, and the editor had also the advantage of using the published labours of his colleague and friend Samuel Prideaux Tregelles.

His edition of the Roman text, with the variants of the Alexandrian manuscript, the Codex Ephraemi, and the Friderico-Augustanus, was of service when it appeared in 1850, but, being stereotyped, was not greatly improved in subsequent issues.

; 1865; 4th edition, 1866, digitized by Google and available for e-readers), Haben wir den echten Schrifttext der Evangelisten und Apostel?