In late October 1884, readers of a contribution to the highly-regarded scientific journal, Nature, were enjoined to place their faith in the measurements of "exact instruments" rather than in the "untrustworthy impressions of the eye" when attempting to draw conclusions about sunsets and other natural phenomena. 1 Spectroscopy, the correspondent implies (in this, his fourth letter to the editors of Nature), is to be preferred to the subjective responses of human observers: colors should be calculable. He dismisses the sunset-speculations of another contributor, the painter Robert Leslie, as being founded more on conjecture and faulty observation than on extrinsic analysis, and sharpens his own critique of subjectivity by insisting that the issue is not merely "a question of terms," but that unsystematic observation can become "a hazardous thing" capable of reversing scientific progress. An explicit connection is drawn between reliance on the personal, untrustworthy eye, and faulty faith in an earth-centered Ptolemaic universe. 2

And then this cold and disciplined scientist suddenly becomes Gerard Manley Hopkins:

If a very clear, unclouded sun is gazed at, it often appears not convex, but hollow; -- swimming, like looking down into a boiling pot or swinging pail, or into a bowl of quicksilver shaken: and of a lustrous but indistinct hue.3

The remainder of Hopkins' letter to Nature is of a tenor his modern readers might recognize and expect. The poet who wrote so triumphantly and idiosyncratically of skyscapes in verse, who kissed his hand "to the dappled-with-damson west" and recorded the "lovely behaviour/ Of silk-sack clouds" of which no "wilder, wilful-wavier/ Meal-drift moulded ever and melted across skies" now seems to reverse his somber, scientific position and embrace the act of human observation.4 He revels in subjective metaphormaking, writing of the colors of a sunset (however objectively noted to have occurred between 6:15 and 6:30 Dublin time on October 19th, 1884) as "bronzy near the earth; above like peach, or of the blush colour on ripe hazels."5 Personal observation is revalued, both through Hopkins' evocative prose and his admission that commonplace but previously-unremarked natural occurrences may be revealed, not by the use of spectroscopes and anemometers, but by individuals in whom the "untrustworthy eye" has been made "unusually observant."6 It is difficult not to identify the writer of this letter as one of those privileged observers, particularly when he closes by offering his own record of a strange phenomenon -- a blue-tinged sunset:

Even since writing the above I have witnessed, though slightly, the phenomenon of a blue setting. The sunset was bright this evening, the sun of a ruddy gold, which colour it kept till nothing was left of it but a star-like spot; then this spot turned. for the twinkling of an eye, a leaden or watery blue, and vanished.7

The conditions under which subjective witnesses become "unusually observant," and therefore, in Hopkins' view, more capable of making observations of scientific value, seem to be twofold. The first is intrinsic -- a state of the psyche and the soul, an effect of education and temperament, a brand of intemalized tectonic drift. The second is extrinsic and sometimes volcanically catastrophic -- having to do with the events of the physical world, over which the observer has no measure of control, but which alert him and heighten his senses and lift veils to let him see.