About the nature of the seasons

Know that these seasons for doctors are not the same as for astronomers. Astronomers have four seasons - these periods of successive transition of the sun from one quarter of the zodiac to another, starting from the point of the vernal equinox, and for doctors, spring is a time when in temperate countries no significant warming is required due to cold or much some significant relief from the heat, and when the trees begin to grow. Spring time is the period between the vernal equinox - it can begin a little earlier or a little later - before the sun enters half of the constellation Taurus. In countries like ours, autumn is a period corresponding in length to spring; in other countries, spring may begin earlier and autumn later.

Summer is the entire period of heat, and winter is the entire period of cold. Spring and autumn - each of these periods - is, according to doctors, shorter than each of the other periods, that is, summer and winter. The winter period corresponds in length to summer or lasts less or longer, depending on the country. It seems that spring is the time of flowers and the beginning of fruits, and autumn is the time of changing color of leaves and the beginning of their fall; other periods are winter and summer.

We say: the nature of spring is a balanced nature, and not hot and humid, as some people think, but a deep study of this is part of the science of nature, which relates to philosophy. Let us consider it indisputable that spring is a balanced period, and summer is hot and dry due to the proximity of the sun to the zenith, and the strength of the rays emanating from it, which in summer appear to be reflected either at a very acute angle, or returning back along the same lines along which they fell. At the same time, the rays seem to thicken. In fact, the reason for this is that it is as if the place where the rays of the sun fall is a cone with an axis in the form of a cylinder, and this cone seems to emanate from the center of the body of the sun, falling on what is opposite to it. Sometimes the place where the sun's rays fall is a plane, a circle, or a figure close to a circle. The strength of the rays of the sun at the axis is greatest, since their action is directed towards the axis from all ends, and in the places adjacent to the ends it is weaker. We are in the summer on the axis or close to it, and this period continues for us, the inhabitants of northern latitudes, for a long time. And in winter we are kind of on the edges.

That is why the light of the sun is brighter in summer, although the distance from the place where we are to the sun, which is close to its apogee, is greater. The relative degree of this closeness and distance is explained in the astronomy department of the mathematical part of philosophy, and the study of the increase in heat due to the increase in light of the sun is explained in the natural history part of philosophy.

Summer, being hot, is at the same time dry due to the evaporation of moisture from intense heat, from the rarefaction of air substances, which is likened to the nature of fire, and also from the fact that little dew and rain fall in summer. Winter is cold and wet for reasons opposite to those described above.

As for autumn, in autumn the heat decreases, while the cold has not yet strengthened. At this time of year,  we seem to find ourselves, in relation to distance, in the middle between the mentioned axis and the edges; therefore, autumn is close to balanced in terms of heat and cold, but it is not balanced in terms of humidity and dryness. And how can this be if the sun has dried out the air and has not yet created humidifying factors to counter the drying effect of the drying factors.

With regard to cooling the situation is different than with humidification, for the transition to a cold state occurs with ease, but the transition to a wet state does not occur with such ease. Moreover, the transition to moisture due to cold is not the same as the transition to dryness due to heat, for the transition to dryness due to heat occurs with ease: after all, the slightest heat already dries, while the slightest cold does not yet moisten. On the contrary, it sometimes happens that the slightest heat acts more strongly in the sense of moistening, when there is an insignificant amount of cold in the matter, for the slightest heat turns moisture into steam, but does not dissipate it, while the slightest cold does not thicken or collect moisture. Therefore, spring does not preserve the moisture of winter to the same extent as autumn preserves the dryness of summer, for the moisture of spring is balanced by the heat of summer in such a period of time during which the dryness of autumn does not have time to be balanced by the cold of winter. It seems that this moistening and drying is similar to the action and lack of action of a certain ability, but not to the action of two opposite principles, for drying here is nothing more than the deprivation of something wet substance, and moistening is not the deprivation of something dry substance, but delivery of a wet substance. After all, we do not say here: “moist air” and “dry air,” meaning natural form or natural quality - in this case this does not even apply here or applies to a small extent. When we say “moist air,” we only mean “air to which thick water vapor has been mixed,” or “air that has become, through condensation, something like water vapor.” In this sense, we say: “dry air,” that is, air from which water vapor mixed with it has come out, or due to rarefaction has acquired a resemblance to a fiery substance, or earthly vapor has been mixed in with it, similar to earth in its moisture-absorbing effect.

In spring, excess winter moisture is destroyed by the slightest heat, which occurs as a result of the sun approaching its zenith, while in autumn, the slightest cold does not cause the air to become humid. If you want to know this, then see whether dry things become damp in cold air, how wet things dry in hot air, if we assume that cold air is approximately the same in degree of coldness as hot air is in warmth.

When you observe this, you will see that the situation in these two cases is different.

However, there is another reason, more important: the fact is that moisture is retained in both cold and hot air only with a constant influx of reinforcement with new moisture, and drying does not need reinforcement at all. Moisture in bodies open to air or in the air itself is retained only due to reinforcement, because the air is called very cold only in relation to our body. After all, the coldness of the air in inhabited countries, in our opinion, never reaches such a degree that there is absolutely no dissolution; on the contrary, in all circumstances dissolution occurs, since the force of the sun and stars acts in the air; when the supply of moisture stops and dissolution continues, drying occurs faster. And in the spring, more dissolves than turns into steam. The reason for this is that the transformation into steam is produced by two circumstances: a small, light heat in the external air and intense heat hidden in the earth, a small part of which reaches the space close to the surface of the earth. In winter, the interior of the earth is warm and even very hot, as explained in the basic natural sciences, and the heat of the air is small. In this case, both causes of humidification are combined, that is, the raising of vapors and their condensation, especially since cold also produces condensation and transformation into vapor in the substance of the air itself.

And in the spring, the air dissolves more than it turns into steam. The internal latent heat of the earth is greatly reduced; that part of this heat that is directed to the surface of the earth comes out of the depths, driven by the principle that has firmly captured the substance and is therefore stronger than the principle that turns into steam or that which only slightly turns into steam; this principle liquefies the substance, since its easy transformation into steam meets the increased heat in the air and thanks to this, complete dissolution occurs. We say this in accordance with what happens most often, in accordance with each of the mentioned causes separately, but not with other causes that cause phenomena other than those we are talking about.

Further, in the spring there is no abundance of matter that would overtake what rises and liquefies. Therefore, the nature of spring should be inclined towards balance in relation to moisture and dryness, just as it is balanced in relation to heat and cold, although we do not consider it impossible that the beginning of spring should be more prone to humidity. However, this moisture is not as far from balance as the dry nature of autumn is from balance. 6

Then I will say: anyone who does not consider autumn to be very balanced in terms of both warmth and cold is not far from the truth. After all, the external signs of autumn are summer ones, for the autumn air is very dry and well prepared to perceive heating and to transform into a kind of fiery substance, since summer predisposed it to this. And the nights and mornings in autumn are cold, because the sun during this period is distant from the zenith, and also because everything rare and rarefied is very susceptible to the influence of the cooling principle.

And spring is nearer to equilibrium in regard to both these qualities, for a cause similar to that which operates in autumn does not produce in the spring air the heating and cooling which it produces in the air in autumn; therefore, the night in spring is not very different from the day. If someone asks: “Why are autumn nights colder than spring, although in autumn the air should be warmer, since it is thinner?” - then we will say in response: very rarefied air is more likely to receive heat and cold in the same way as very rarefied water. - Therefore, if you heat water and subject it to freezing, it will freeze sooner than cold water, for cooling will pass through it more easily due to its sparseness. However, spring cold is not as sensitive to the body as autumn cold, for bodies that move from cold to warmth in spring are accustomed to cold, and in autumn - vice versa. Moreover, autumn is moving towards winter, and spring is moving away from it.

Know that the change of season produces some type of disease in every climate. The physician needs to know this well in relation to each climate, so that the precautions and prescription of the regimen are based on genuine knowledge. Some days, unlike others, also resemble one or another time of year: there are winter days, there are summer days, and there are autumn days, sometimes it can be hot and cold on the same day.