ENCYCLOPÆDIA BRITANNICA.
PHY - PHY
PHYLACTERY (φυλακτήριον) is the name given in the New Testament to the חהלן (tefillîn) or "prayer-thongs" of the Jews. Every Jew wears at prayer two of these thongs—(1) the hand-tefilla, a leather thong wound round the left arm and supporting a small case containing a parchment strip with the passages Exod. xiii. 1-10, 11-16, Deut. vi. 4-9, xi. 13-21 written in four columns; (2) the head-tefilla, a similar thong with the four passages inscribed on four separate slips of parchment, and worn round the head so that the box with the texts rests on the forehead. The use of these phylacteries is justified by a literal interpretation of expressions in the passages above cited, and they form, together with the צ׳צ׳ח (zizith) or "fringe" (Numb. xv. 37 sq.) and the מזחה (mezûza) above the door, the three sets of visible signs by which the Israelite is constantly reminded of his duty to God. The zizith is no longer placed on the outer garment as in New Testament times (Matt. xxiii. 5), but on the woollen scarves called טל׳ח (tallîth), of which the Jewish man always wears one, while another is wound round the head and neck during prayer. The mezûza is now a longish box fixed over the right doorpost of houses or rooms and containing a parchment with Deut. vi. 4-9, xi. 13-21.
In their origin there can be little doubt that the phylacteries are, according to the proper sense of the Greek word, a kind of amulet, not essentially different from the Aramaic kmi 6, and in fact "the Hebrew" of the Hexapla uses the word "phylacteries" for the amulets (E. V. pillows) of Ezek. xiii. 18. Phylactery and mezûza were supposed to keep off hurtful demons (Targ. on Cant. viii. 3). For further particulars, see Surenhusius, Mishna, i. 9 sq., and Bodenschatz, Kirch. Verf. d. heutigen Juden, iv. 9 sq.
PHYLLOXERA.See Vine.
PHYSICAL CONSTANTS.See Weights and Measures.
PHYSICAL GEOGRAPHY.See vol. x. pp. 210-212.
PHYSICAL SCIENCES.[1]According to the original meaning of the word, physical science would be that knowledge which is conversant with the order of nature—that is, with the regular succession of events whether mechanical or vital in so far as it has been reduced to a scientific form. The Greek word "physical" would thus be the exact equivalent of the Latin word "natural." In the actual development, however, of modern science and its terminology these two words have come to be restricted each to one of the two great branches into which the knowledge of nature is divided according to its subject-matter. Natural science is now understood to refer to the study of organized bodies and their development, while physical science investigates those phenomena primarily which are observed in things without life, though it does not give up its claim to pursue this investigation when the same phenomena take place in the body of a living being. In forming a classification of sciences the aim must be to determine the best arrangement of them in the state in which they now exist. We therefore make no attempt to map out a scheme for the science of future ages. We can no more lay down beforehand the plan according to which science will be developed by our successors than we can anticipate the particular discoveries which they will make. Still less can we found our classification on the order in time according to which different sciences have been developed. This would be no more scientific than the classification of the properties of matter according to the senses by which we have become acquainted with their existence.
It is manifest that there are some sciences, of which we may take arithmetic as the type, in which the subject-matter is abstract, capable of exact definition, and incapable of any variation arising from causes unknown to us which would in the slightest degree alter its properties. Thus in arithmetic the properties of numbers depend entirely on the definitions of these numbers, and these definitions may be perfectly understood by any person who will attend to them. The same is true of theoretical geometry, though, as this science is associated in our minds with practical geometry, it is difficult to avoid thinking of the probability of error arising from unknown causes affecting the actual measurement of the quantities. There are other sciences, again, of which we may take biology as the type, in which the subject-matter is concrete, not capable of exact definition, and subject to the influence of many causes quite unknown to us. Thus in
- ↑ The paper of the late Professor J. Clerk Maxwell which is presented to the reader under this head was prepared at the time when the ninth edition of the Encyclopaedia Britannica was being planned, and bore in his MS. the title "Remarks on the Classification of the Physical Sciences."
