The Notebooks of Leonardo Da Vinci — Complete
Andrea Corsali's letters to Giuliano de'Medici: _Alcuni gentili
chiamati Guzzarati non si cibano di cosa, alcuna che tenga sangue,
ne fra essi loro consentono che si noccia ad alcuna cosa animata,
come il nostro Leonardo da Vinci_.
5-18. Amerigo Vespucci, with whom Leonardo was personally
acquainted, writes in his second letter to Pietro Soderini, about
the inhabitants of the Canary Islands after having stayed there in
1503: "_Hanno una scelerata liberta di viuere; ... si cibano di
carne humana, di maniera che il padre magia il figliuolo, et
all'incontro il figliuolo il padre secondo che a caso e per sorte
auiene. Io viddi un certo huomo sceleratissimo che si vantaua, et si
teneua a non piccola gloria di hauer mangiato piu di trecento
huomini. Viddi anche vna certa citta, nella quale io dimorai forse
ventisette giorni, doue le carni humane, hauendole salate, eran
appicate alli traui, si come noi alli traui di cucina_ _appicchiamo
le carni di cinghali secche al sole o al fumo, et massimamente
salsiccie, et altre simil cose: anzi si marauigliauano gradem ete
che noi non magiaissimo della carne de nemici, le quali dicono
muouere appetito, et essere di marauiglioso sapore, et le lodano
come cibi soaui et delicati (Lettere due di Amerigo Vespucci
Fiorentino drizzate al magnifico Pietro Soderini, Gonfaloniere della
eccelsa Republica di Firenze_; various editions).]
845.
Our life is made by the death of others.
In dead matter insensible life remains, which, reunited to the
stomachs of living beings, resumes life, both sensual and
intellectual.
846.
Here nature appears with many animals to have been rather a cruel
stepmother than a mother, and with others not a stepmother, but a
most tender mother.
847.
Man and animals are really the passage and the conduit of food, the
sepulchre of animals and resting place of the dead, one causing the
death of the other, making themselves the covering for the
corruption of other dead [bodies].
On the circulation of the blood (848-850).
848.
Death in old men, when not from fever, is caused by the veins which
go from the spleen to the valve of the liver, and which thicken so
much in the walls that they become closed up and leave no passage
for the blood that nourishes it.
[6]The incessant current of the blood through the veins makes these
veins thicken and become callous, so that at last they close up and
prevent the passage of the blood.
849.
The waters return with constant motion from the lowest depths of the
sea to the utmost height of the mountains, not obeying the nature of
heavier bodies; and in this they resemble the blood of animated
beings which always moves from the sea of the heart and flows
towards the top of the head; and here it may burst a vein, as may be
seen when a vein bursts in the nose; all the blood rises from below
to the level of the burst vein. When the water rushes out from the
burst vein in the earth, it obeys the law of other bodies that are
heavier than the air since it always seeks low places.
[Footnote: From this passage it is quite plain that Leonardo had not
merely a general suspicion of the circulation of the blood but a
very clear conception of it. Leonardo's studies on the muscles of
the heart are to be found in the MS. W. An. III. but no information
about them has hitherto been made public. The limits of my plan in
this work exclude all purely anatomical writings, therefore only a
very brief excerpt from this note book can be given here. WILLIAM
HARVEY (born 1578 and Professor of Anatomy at Cambridge from 1615)
is always considered to have been the discoverer of the circulation
of the blood. He studied medicine at Padua in 1598, and in 1628
brought out his memorable and important work: _De motu cordis et
sanguinis_.]
850.
That the blood which returns when the heart opens again is not the
same as that which closes the valves of the heart.
Some notes on medicine (851-855).
851.
Make them give you the definition and remedies for the case ... and
you will see that men are selected to be doctors for diseases they
do not know.
852.
A remedy for scratches taught me by the Herald to the King of
France. 4 ounces of virgin wax, 4 ounces of colophony, 2 ounces of
incense. Keep each thing separate; and melt the wax, and then put in
the incense and then the colophony, make a mixture of it and put it
on the sore place.
853.
Medicine is the restoration of discordant elements; sickness is the
discord of the elements infused into the living body.
854.
Those who are annoyed by sickness at sea should drink extract of
wormwood.
855.
To keep in health, this rule is wise: Eat only when you want and
relish food. Chew thoroughly that it may do you good. Have it well
cooked, unspiced and undisguised. He who takes medicine is ill
advised.
[Footnote: This appears to be a sketch for a poem.]
856.
I teach you to preserve your health; and in this you will succed
better in proportion as you shun physicians, because their medicines
are the work of alchemists.
[Footnote: This passage is written on the back of the drawing Pl.
CVIII. Compare also No. 1184.]
_XV_.
_Astronomy_.
_Ever since the publication by Venturi in_ 1797 _and Libri in_ 1840
_of some few passages of Leonardo's astronomical notes, scientific
astronomers have frequently expressed the opinion, that they must
have been based on very important discoveries, and that the great
painter also deserved a conspicuous place in the history of this
science. In the passages here printed, a connected view is given of
his astronomical studies as they lie scattered through the
manuscripts, which have come down to us. Unlike his other purely
scientific labours, Leonardo devotes here a good deal of attention
to the opinions of the ancients, though he does not follow the
practice universal in his day of relying on them as authorities; he
only quotes them, as we shall see, in order to refute their
arguments. His researches throughout have the stamp of independent
thought. There is nothing in these writings to lead us to suppose
that they were merely an epitome of the general learning common to
the astronomers of the period. As early as in the XIVth century
there were chairs of astronomy in the universities of Padua and
Bologna, but so late as during the entire XVIth century Astronomy
and Astrology were still closely allied._
_It is impossible now to decide whether Leonardo, when living in
Florence, became acquainted in his youth with the doctrines of Paolo
Toscanelli the great astronomer and mathematician (died_ 1482_), of
whose influence and teaching but little is now known, beyond the
fact that he advised and encouraged Columbus to carry out his
project of sailing round the world. His name is nowhere mentioned by
Leonardo, and from the dates of the manuscripts from which the texts
on astronomy are taken, it seems highly probable that Leonardo
devoted his attention to astronomical studies less in his youth than
in his later years. It was evidently his purpose to treat of
Astronomy in a connected form and in a separate work (see the
beginning of Nos._ 866 _and_ 892_; compare also No._ 1167_). It is
quite in accordance with his general scientific thoroughness that he
should propose to write a special treatise on Optics as an
introduction to Astronomy (see Nos._ 867 _and_ 877_). Some of the
chapters belonging to this Section bear the title "Prospettiva"
_(see Nos._ 869 _and_ 870_), this being the term universally applied
at the time to Optics as well as Perspective (see Vol. I, p._ 10,
_note to No._ 13, _l._ 10_)_.
_At the beginning of the XVIth century the Ptolemaic theory of the
universe was still universally accepted as the true one, and
Leonardo conceives of the earth as fixed, with the moon and sun
revolving round it, as they are represented in the diagram to No._
897. _He does not go into any theory of the motions of the planets;
with regard to these and the fixed stars he only investigates the
phenomena of their luminosity. The spherical form of the earth he
takes for granted as an axiom from the first, and he anticipates
Newton by pointing out the universality of Gravitation not merely in
the earth, but even in the moon. Although his acute research into
the nature of the moon's light and the spots on the moon did not
bring to light many results of lasting importance beyond making it
evident that they were a refutation of the errors of his
contemporaries, they contain various explanations of facts which
modern science need not modify in any essential point, and
discoveries which history has hitherto assigned to a very much later
date_.
_The ingenious theory by which he tries to explain the nature of
what is known as earth shine, the reflection of the sun's rays by
the earth towards the moon, saying that it is a peculiar refraction,
originating in the innumerable curved surfaces of the waves of the
sea may be regarded as absurd; but it must not be forgotten that he
had no means of detecting the fundamental error on which he based
it, namely: the assumption that the moon was at a relatively short
distance from the earth. So long as the motion of the earth round
the sun remained unknown, it was of course impossible to form any
estimate of the moon's distance from the earth by a calculation of
its parallax_.
_Before the discovery of the telescope accurate astronomical
observations were only possible to a very limited extent. It would
appear however from certain passages in the notes here printed for
the first time, that Leonardo was in a position to study the spots
in the moon more closely than he could have done with the unaided
eye. So far as can be gathered from the mysterious language in which
the description of his instrument is wrapped, he made use of
magnifying glasses; these do not however seem to have been
constructed like a telescope--telescopes were first made about_
1600. _As LIBRI pointed out_ (Histoire des Sciences mathematiques
III, 101) _Fracastoro of Verona_ (1473-1553) _succeeded in
magnifying the moon's face by an arrangement of lenses (compare No._
910, _note), and this gives probability to Leonardo's invention at a
not much earlier date._
I.
THE EARTH AS A PLANET.
The earth's place in the universe (857. 858).
857.
The equator, the line of the horizon, the ecliptic, the meridian:
These lines are those which in all their parts are equidistant from
the centre of the globe.
858.
The earth is not in the centre of the Sun's orbit nor at the centre
of the universe, but in the centre of its companion elements, and
united with them. And any one standing on the moon, when it and the
sun are both beneath us, would see this our earth and the element of
water upon it just as we see the moon, and the earth would light it
as it lights us.
The fundamental laws of the solar system (859-864).
859.
Force arises from dearth or abundance; it is the child of physical
motion, and the grand-child of spiritual motion, and the mother and
origin of gravity. Gravity is limited to the elements of water and
earth; but this force is unlimited, and by it infinite worlds might
be moved if instruments could be made by which the force could be
generated.
Force, with physical motion, and gravity, with resistance are the
four external powers on which all actions of mortals depend.
Force has its origin in spiritual motion; and this motion, flowing
through the limbs of sentient animals, enlarges their muscles. Being
enlarged by this current the muscles are shrunk in length and
contract the tendons which are connected with them, and this is the
cause of the force of the limbs in man.
The quality and quantity of the force of a man are able to give