It is true, sketches, or such drawings as painters generally make for their works, give this pleasure of imagination to a high degree. From a slight, undetermined drawing, where the ideas of the composition and character are, as I may say, only just touched upon, the imagination supplies more than the painter himself, probably, could produce; and we accordingly often find that the finished work disappoints the expectation that was raised from the sketch; and this power of the imagination is one of the causes of the great pleasure we have in viewing a collection of drawings by great painters. These general ideas, which are expressed in sketches, correspond very well to the art often used in Poetry. A great part of the beauty of the celebrated description of Eve in Milton's "Paradise Lost" consists in using only general indistinct expressions, every reader making out the detail according to his own particular imagination,--his own idea of beauty, grace, expression, dignity, or loveliness: but a painter, when he represents Eve on a canvas, is obliged to give a determined form, and his own idea of beauty distinctly expressed. We cannot on this occasion, nor indeed on any other, recommend an undeterminate manner or vague ideas of any kind, in a complete and finished picture. This notion, therefore, of leaving anything to the imagination, opposes a very fixed and indispensable rule in our art--that everything shall be carefully and distinctly expressed, as if the painter knew, with correctness and precision, the exact form and character of whatever is introduced into the picture. This is what with us is called Science and Learning: which must not be sacrificed and given up for an uncertain and doubtful beauty, which, not naturally belonging to our Art, will probably be sought for without success. Mr. Falconet has observed, in a note on this passage in his translation of Pliny, that the circumstance of covering the face of Agamemnon was probably not in consequence of any fine imagination of the painter--which he considers as a discovery of the critics--but merely copied from the description of the sacrifice, as it is found in Euripides. The words from which the picture is supposed to be taken are these: _Agamemnon saw Iphigenia advance towards the fatal altar; he groaned, he turned aside his head, he shed tears, and covered his face with his robe._