Why charcoal is kindled by a crystal when it is placed opposite the sun's rays.
One asks why it is that if a crystal is placed opposite the sun's rays entering through a window of a house or through some opening and if a bit of charcoal or some little piece of food is held behind the crystal from the rear, it is kindled. I have heard that the same thing happens when a bottle filled with water is exposed to the sun.
For this one must know that the crystal has to be made by a congealing coldness. For it is by means of cold that water is congealed into snow, and by a more intense cold it is congealed into hail, and by an even more intense cold it is congealed into a crystal.
Again, one should know that a crystal is naturally moist and contains in itself a certain moisture that is a fomentation [fomentum] for the heat.
And again a crystal is a radiant body that is transparent to the rays of the sun. When, then, it is placed opposite the sun's rays, these rays, penetrating through the most narrow pores into the substance of the crystal, are then made very subtle, and in the crystal they strike one another, and, because of this thinning and striking of the rays, and because there is moisture there, which is a fomentation for the heat, <they ignite>, and when the rays exit from the other side of the crystal they are thinned even more and strike one another and are ignited. Even the air between the crystal and the food is ignitedthat is, it is combustibleand this is why the food itself is ignited. For air is a material that is close to fire, and a very rarified air is changed into fire, and the fire is condensed into heat.
Note that the lion is a choleric animal, namely, very hot and dry, but the burned bile [cholera adusta] is burned in it, and therefore it continuously suffers a quartan fever from the natural melancholy.
Note too that every poison is very dry either in act or in power.
Why snow is preserved in barley chaff.
One asks why it is that snow is preserved in barley chaff.
We say to this that chaff is cold and dry and both barley and snow are very cold. Therefore, since that which is cold has its movement toward the center and since that which is cold and dry also has its movement toward the center, the snow is not dissolved but is preserved undissolved.
Why pears placed in barley chaff become ripe.
Again one inquires why it is that pears placed in barley chaff become ripe.
We say it is because generation has to occur from the heat of the pears. Now there is a certain earthy and crude substance in pears, and a certain moisture exists in pears. Moreover, in pears there is also a certain spiritual and smoky substance. When, then, they are put in the cold and dry chaff of the barley, their pores are constricted, and, once they are constricted, the airy and spiritual substance is retained so that a particular heat is born whose efficacy is increased in the pears. Acting then on the substance, it dissolves and softens it, and so ripening occurs. But if the pears are left for a long time, a greater dissolution occurs than the consumption and purification of the things dissolved can bring about, which is why they rot and sometimes putrefy.
Why women have such large breasts, and men do not.
One asks why it is that women have such large breasts, and men do not.
One must reply that there is a threefold cause, namely, a final, a material, and an efficient cause. The final cause is this: infants do not have instruments suitable for chewing and grinding up hard and solid foods, and this is why provident and pious nature established certain instruments, namely, loose-textured and spongy breasts, within which a blood-filled mass might be received and bubble up. And by means of this bubbling action a certain white sweetness, set free from the substance of the breasts, whitens it, and so too by this bubbling action it is converted into the milk on which the fetus is nourished.
Another reason is that some veins proceed from the liver to the womb and on the way they split into two. One branch extends to the breasts and the other to the womb.
Again, the womb is joined to certain veins that intersect the middle of the breasts. Therefore, the bloody mass and superfluity contained in the womband especially a mass of melancholy bloodare sent through the branches and through these veins in large quantity, and in a quantity even greater than is needed or which suffices for the nourishment of the breasts. By means of the heat and motion of the heart, which is placed under it, the mass bubbles up, and, once digested and dried out by this bubbling action, it is changed into the essence or substance of the breasts. And this is why the breasts of women become large and grow.
The material cause is the great moisture that is in women. For a woman is naturally conceived from the matter of the [moist] humor. Then, the heat acts on such great moisture present in the breasts, digests it, decocts it, and changes it into the essence of the breasts. Therefore, the breasts become large, and moisture is the material cause.
Heat coming from the heart is the efficient cause. Thus the breasts are naturally conceived from a drier material.
Know too that the breasts grow more from the fourteenth year, when women begin to menstruate, because then the superfluities of all of the humors and of the melancholy blood flow together to the womb, and these, when turned back in large amounts to the breasts, are the cause of large breasts. But before the time of menstruation the superfluities do not flow so much to the womb. The breasts increase a great deal in pregnant women, because the superfluities, which are customarily cleansed by menstruation, are then retained in large quantity and sent to the breasts and are a cause of large breasts.