Henry Peacham (1576-1643) was an English poet and writer, best known for his guide to Renaissance arts and manners, The Compleat Gentleman (1622). In it he defines the word “conservative” as “that power of promoting care, stewardship, learning, and healthfulness whilst opposing diminution, detriment, ignorance, and injury.”
In one magnificent example of his Elizabethan and Jacobite prose he describes, "That spherical figure, as to all heavenly bodies, so it agreeth to light, as the most perfect and conservative of all others."
According to Samuel Johnson, in his incomparable Dictionary (1755), it is from this term and its incumbent meaning that the word “conservatory” is derived. Thus, he defines it as “A place where anything is kept in a manner proper to its peculiar nature, as fish in a pond, corn in a grainary, or culture in the heart of a student.”