“To Boerhaave, therefore—especially considering his great influence as a teacher of chemistry—we may assign the merit of first diffusing a proper view of chemical affinity as a peculiar force, the origin of almost all chemical changes and operations.”— William Whewell (1840), “The Establishment and Development of the Idea of Chemical Affinity” 
|“Non igitur hic etiam actiones mechanica, non propulsiones violentae, non inimicitiae cogitandae, sed amicitiae, si amor dicendus copulae cupido. Fateor, paradoxa haec assertio.”||“Here, too, [when a solvent dissolves a solvent] the mechanical action is not, therefore, a force, by violence, nor private hatred thought about, but of friendship, if ‘love’ is to be called their union, in the desire for a praise. Yes, this is a paradoxical assertion.”|
“When we make a chemical solution, not only are the particles of the dissolved body separated from each other, but they are closely united to the particles of the solvent. When aqua regia dissolves gold, do we not see that there must be between each particle of the solvent and of the metal, a mutual virtue by which each loves, unites with, and holds the other (amat, unit, retinet)?”— Herman Boerhaave (1732), Elements of Chemistry (pg. 677); cited by Whewell (1840) (Ѻ)
“In 1775, the Swedish chemist Bergman, pursuing still further this subject of chemical affinities, and the expression of them by means of tables, returned again to the old Newtonian term; and designated the disposition of a body to combine with one rather than another of two others as elective attraction. And as his work on Elective Attractions had great circulation and great influence, this phrase has obtained a footing by the side of affinity, and both one and the other are now in common use among chemists.
There are some analogies drawn from the common meaning of this word, which appear to recommend it as suitable for the office which it has to discharge. For common mechanical attractions and repulsions, the forces by which one body considered as a whole acts upon another external to it, are, as we have said, to be distinguished from those more intimate ties by which the parts of each body are held together. Now this difference is implied, if we compare the former relations, the attractions and repulsions, to alliances and wars between states, and the latter, the internal union of particles, to those bonds of affinity which connect the citizens of the same state with one another, and especially to the ties of family.
We have seen that Boerhaave compares the union of two elements of a compound to their marriage; “we must allow,” says an eminent chemist [Jean Dumas, 1837] of our own time”, “that there is some truth in this poetical comparison.” It contains this truth, that the two become one to most intents and purposes, and that the unit thus formed (the family) is not a mere juxtaposition of the component parts. And thus the idea of affinity as the peculiar principle of chemical composition, is established among chemists, and designated by a familiar and appropriate name.”
“One should have continually before one’s eyes these two perfect models that the two great men of the century have left us: the Opticks of Newton and the Chemistry of Boerhaave.”— Pieter Musschenbroek (c.1734), Publication 
“Although we are able to discuss the ‘force of fire’ by its sensible effects; yet, we cannot from its force make certain judgments of its quantity.”— Herman Boerhaave (1724), Elements of Chemistry (pgs. 153) 
“It is demonstrated by the geometers that if bodies remain the same in all other circumstances, the bigger they are the less surface they will always have in proportion to their solidity.”— Herman Boerhaave (1724), Elements of Chemistry (pg. 160-61) 
“Among all the bodies of the universe, that have hitherto been discovered and examined, there never was yet found any one, that had spontaneously, and of its own nature, a greater degree of heat than any other.”— Herman Boerhaave (1724), Elements of Chemistry (pgs. 166) 
“Air of unequal masses, but of the same density, is always expanded in the same measure by the same ‘degree of fire’; so that these expansions in the same density of air, by a constant law of nature, are always proportional to the augmentations of heat.”— Herman Boerhaave (1732), Elements of Chemistry; as cited and dated by W.S. James (1929)