  On the basis of his `Z\"urich Notebook' I shall describe a particularly
fruitful phase in Einstein's struggle on the way to general relativity. These
research notes are an extremely illuminating source for understanding
Einstein's main physical arguments and conceptual difficulties that delayed his
discovery of general relativity by about three years. Together with the
`Ent\-wurf' theory in collaboration with Marcel Grossmann, these notes also
show that the final theory was missed late in 1912 within a hair's breadth. The
Einstein-Grossmann theory, published almost exactly hundred years ago,
contains, however, virtually all essential elements of Einstein's definite
gravi\-tation theory. This should become obvious by our streamlined
presentation of the final phase in November 1915 that culminated with the
definite field equations.
