From the starting-point of the book of which the printer printed nothing but the text the collector can advance in many different directions. There was no regular and unbroken progress in the development of the modern form of book, nor does it matter greatly that the examples of any particular improvement should be either absolutely or nearly the earliest. The main thing is that they should be good illustrations of the special feature for which they are acquired. The problem how to dispense with the aid of a rubricator had to be faced by countless printers in many different towns, for rubricating by hand must have added very considerably to the cost of a book. The obvious thing to do was to print in red all the headings, chapter-numbers, etc., which the rubricator used to add in that colour. But this was both expensive and troublesome, as it involved two printings and the placing of the paper in exactly the same position in the press in each. Caxton and one or two other early printers tried to avoid this double printing and difficulty of registration by putting on both red and black ink at the same time--very probably, where they came close together, they were rubbed on with a finger--but this so often resulted in smudges and lines half of one colour, half of another, that it was soon abandoned. Double printing was mostly soon abandoned also, except by the most expert men. It was tried and abandoned by the printer of the Forty-two Line Bible, though subsequently Fust and Schoeffer completely mastered it. Between 1472 and 1474 it was tried and abandoned by almost every printer in Strassburg. The difficulty was generally[28] overcome by substituting, for red ink used with type of the same size or face as the text, type of a larger size or heavier face, which could be printed in black ink with the text and yet stand out sufficiently clearly from it to catch the eye.