The English clergyman Stephen Hales published a remarkable
book in 1727 entitled ‘Vegetable Staticks.’
This classic summarized pioneering studies on plant
physiology that included experiments aimed at explaining
how the sun affects plants. Hales concluded
that
one of the great uses of leaves is what has been
long suspected by many, viz., to perform in some
measure the same office for the support of the
vegetable life, that the lungs of animals do, for
the support of animal life; Plants very probably
drawing thro’ their leaves some part of their nourishment
from the air....And may not light also, by
freely entering the expanded surfaces of leaves and
flowers, contribute much to ennobling principles
of vegetables.