Leonardo's scientific and technical observations are found
in his handwritten manuscripts, of which over 4000 pages survive. It seems
that Leonardo planned to publish them as a great encyclopedia of knowledge,
but like many of his projects, this one was never finished. The manuscripts
are difficult to read: not only did Leonardo write in mirror-image script
from right to left, but he used peculiar spellings and abbreviations, and
his notes are not arranged in any logical order. After his death his notes
were scattered to libraries and collections all over Europe. While portions
of Leonardo's technical treatises on painting were published as early as 1651,
the scope and caliber of much of his scientific work remained unknown until
the 19th century. Yet his geological and paleontological observations and
theories foreshadow many later breakthroughs.