Page:EB1911 - Volume 01.djvu/107

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ABSOLUTION—ABSORPTION OF LIGHT

The whole controversy is obscured by inevitable difficulties in terminology. The fundamental problem is whether a thing which is by hypothesis infinite can in any sense be defined, and if it is not defined, whether it can be said to be cognized or thought. It would appear to be almost an axiom that anything which by hypothesis transcends the intellect (i.e. by including subject and object, knowing and known) is ipso facto beyond the limits of the knower. Only an Absolute can cognize an absolute.


ABSOLUTION (Lat. absolutio from absolvo, loosen, acquit), a term used in civil and ecclesiastical law, denoting the act of setting free or acquitting. In a criminal process it signifies the acquittal of an accused person on the ground that the evidence has either disproved or failed to prove the charge brought against him. In this sense it is now little used, except in Scottish law in the forms assoilzie and absolvitor. The ecclesiastical use of the word is essentially different from the civil. It refers not to an accusation, but to sin actually committed (after baptism); and it denotes the setting of the sinner free from the guilt of the sin, or from its ecclesiastical penalty (excommunication), or from both. The authority of the church or minister to pronounce absolution is based on John xx. 23; Matt. xviii. 18; James v. 16, &c. In primitive times, when confession of sins was made before the congregation, the absolution was deferred till the penance was completed; and there is no record of the use of any special formula. Men were also encouraged, e.g. by Chrysostom, to confess their secret sins secretly to God. In course of time changes grew up. (1) From the 3rd century onwards, secret (auricular) confession before a bishop or priest was practised. For various reasons it became more and more common, until the fourth Lateran council (1215) ordered all Christians of the Roman obedience to make a confession once a year at least. In the Greek church also private confession has become obligatory. (2) In primitive times the penitent was reconciled by imposition of hands by the bishop with or without the clergy: gradually the office was left to be discharged by priests, and the outward action more and more disused. (3) It became the custom to give the absolution to penitents immediately after their confession and before the penance was performed. (4) Until the Middle Ages the form of absolution after private confession was of the nature of a prayer, such as “May the Lord absolve thee”; and this is still the practice of the Greek church. But about the 13th century the Roman formula was altered, and the council of Trent (1551) declared that the “form” and power of the sacrament of penance lay in the words Ego te absolvo, &c., and that the accompanying prayers are not essential to it. Of the three forms of absolution in the Anglican Prayer Book, that in the Visitation of the Sick (disused in the church of Ireland by decision of the Synods of 1871 and 1877) runs “I absolve thee,” tracing the authority so to act through the church up to Christ: the form in the Communion Service is precative, while that in Morning and Evening Prayer is indicative indeed, but so general as not to imply anything like a judicial decree of absolution. In the Lutheran church also the practice of private confession survived the Reformation, together with both the exhibitive (I forgive, &c.) and declaratory (I declare and pronounce) forms of absolution. In granting absolution, even after general confession, it is in some places still the custom for the minister, where the numbers permit of it, to lay his hands on the head of each penitent.  (W. O. B.) 


ABSOLUTISM, in aesthetics, a term applied to the theory that beauty is an objective attribute of things, not merely a subjective feeling of pleasure in him who perceives. It follows that there is an absolute standard of the beautiful by which all objects can be judged. The fact that, in practice, the judgments even of connoisseurs are perpetually at variance, and that the so-called criteria of one place or period are more or less opposed to those of all others, is explained away by the hypothesis that individuals are differently gifted in respect of the capacity to appreciate. (See Aesthetics.)

In political philosophy absolutism, as opposed to constitutional government, is the despotic rule of a sovereign unrestrained by laws and based directly upon force. In the strict sense such governments are rare, but it is customary to apply the term to a state at a relatively backward stage of constitutional development.


ABSORPTION OF LIGHT. The term “absorption” (from Lat. absorbere) means literally “sucking up” or “swallowing,” and thus a total incorporation in something, literally or figuratively; it is technically used in animal physiology for the function of certain vessels which suck up fluids; and in light and optics absorption spectrum and absorption band are terms used in the discussion of the transformation of rays in various media.

If a luminous body is surrounded by empty space, the light which it emits suffers no loss of energy as it travels outwards. The intensity of the light diminishes merely because the total energy, though unaltered, is distributed over a wider and wider surface as the rays diverge from the source. To prove this, it will be sufficient to mention that an exceedingly small deficiency in the transparency of the free aether would be sufficient to prevent the light of the fixed stars from reaching the earth, since their distances are so immense. But when light is transmitted through a material medium, it always suffers some loss, the light energy being absorbed by the medium, that is, converted partially or wholly into other forms of energy such as heat, a portion of which transformed energy may be re-emitted as radiant energy of a lower frequency. Even the most transparent bodies known absorb an appreciable portion of the light transmitted through them. Thus the atmosphere absorbs a part of the sun’s rays, and the greater the distance which the rays have to traverse the greater is the proportion which is absorbed, so that on this account the sun appears less bright towards sunset. On the other hand, light can penetrate some distance into all substances, even the most opaque, the absorption being, however, extremely rapid in the latter case.

The nature of the surface of a body has considerable influence on its power of absorbing light. Platinum black, for instance, in which the metal is in a state of fine division, absorbs nearly all the light incident on it, while polished platinum reflects the greater part. In the former case the light penetrating between the particles is unable to escape by reflexion, and is finally absorbed.

The question of absorption may be considered from either of two points of view. We may treat it as a superficial effect, especially in the case of bodies which are opaque enough or thick enough to prevent all transmission of light, and we may investigate how much is reflected at the surface and how much is absorbed; or, on the other hand, we may confine our attention to the light which enters the body and inquire into the relation between the decay of intensity and the depth of penetration. We shall take these two cases separately.

Absorptive Power.—When none of the radiations which fall on a body penetrates through its substance, then the ratio of the amount of radiation of a given wave-length which is absorbed to the total amount received is called the “absorptive power” of the body for that wave-length. Thus if the body absorbed half the incident radiation its absorptive power would be 1/2, and if it absorbed all the incident radiation its absorptive power would be 1. A body which absorbs all radiations of all wave-lengths would be called a “perfectly black body.” No such body actually exists, but such substances as lamp-black and platinum-black approximately fulfil the condition. The fraction of the incident radiation which is not absorbed by a body gives a measure of its reflecting power, with which we are not here concerned. Most bodies exhibit a selective action on light, that is to say, they readily absorb light of particular wave-lengths, light of other wave-lengths not being largely absorbed. All bodies when heated emit the same kind of radiations which they absorb—an important principle known as the principle of the equality of radiating and absorbing powers. Thus black substances such as charcoal are very luminous when heated. A tile of white porcelain with a black pattern on it will, if heated red-hot, show the pattern bright on a darker ground. On the other hand, those substances which either are good reflectors or