Robert Silverberg published his first story in a professional (paid) science fiction publication in 1954 when he was 19. His career started after the end of the so-called Golden Age of Science Fiction. No writer, fan, critic or academic has counted him as a member of the later movement. He presented himself as an professional writer. He was recognized by several Hugo, Nebula and Locus awards. He retired in 1975, but later wrote more successful fiction. He edited several anthologies, many of which are listed in the Wikipedia bibliography of his work.
World of Wonders, was published by Random House in 1987. It was reprinted in paperback in 2001, retitled Science Fiction 101.
In the Forward, he explained his ideas about the boundaries of fiction, and fantasy and science fiction:
“ ‘Mainstream’ fiction takes place in a world directly derived from ... our own generally perceived reality ... Science fiction though, is a branch of fantasy; it draws on the realities of our world at one remove, attempting to portray not that which we know exists but that which we know does not exist. At its purest extreme, fantasy portrays that which we know cannot exist, and tries to make the impossible plausible. The subset of fantasy that we call science fiction also aims for plausibility, but instead of dealing with impossibilities ... it works with that which that which is or seems possible but not yet a reality ... and tries to give unrealities the air of reality or, for the nonce, coaxing from the reader ‘a willing suspension of disbelief’. That famous phrase of Coleridge beautifully describes what any writer ... must strive to achieve.
“... The fantasist [evokes the suspension] by producing fiction that is realistic at its core, built upon rigorously held and internally consistent perceptions and assumptions ... they must have a strict inner reality of their own.”
Near the end, in his essay on Frederick Pohl's 1966 story "Day Million", he says:
"All science fiction, as I indicated ... is in truth fantasy; ... there are degrees of fantasy. ... The dividing point is the matter of probability. .... ... it's possible to identify different levels of probability.
" ... different [appoaches] [by writers] to the problem of making a wildly improbable situation look plausible. ... because Fred Pohl has taken immense care to ground his fantastic assumptions in many aspects of contemporary science and technology, his fiction carries a kind of conviction ..."
Silverberg’s Introduction to World of Wonders subtitled “The Making of a Science-Fiction Writer”, recalls his childhood reading of the genre in the pulp magazines and available anthologies. It offers facts that he recalls as a reader in the '40s:
• the New York Public library classified science fiction under the heading “Pseudoscientific Literature”;
• Donald Wollheim’s (fan, writer, anthologist, one of the founders of the Futurians) Pocket Book of Science Fiction (1943) was the first paperback science fiction anthology.
Most of the Introduction describes Silverberg’s efforts, as a teenager, to learn about the technique of writing a story. Silverberg read science fiction. Silverberg read articles and essays by James Blish/> in a small magazine – later collected in The Issue at Hand (1964.) and made himself Blish’s disciple. He met Blish around 1950-51. It may have been on the periphery of the New York Futurian group. Silverberg read essays and criticism by Damon Knight, another New York Futurian, published in published magazines (collected in In Search of Wonder, (1956). He planned his own work to avoid the things that Blish and Knight criticized. In 1954 Silverberg bought and read Greek Tragedy (1939) by the British scholar H.D.F. Kitto/>. In 1953,Silverberg began submitting stories to Galaxy and receive criticism from the editor, Horace Gold. He discussed the criticism with SF writers in New York (Futurians) including Frederick Pohl, Lester del Rey, Theodore Sturgeon, Judith Merrill, Algys Budrys and Cyril Kornbluth. He was self-taught, but had the benefits of an ongoing masterclass writing SF. It would hard to get the same education in 1987, or in the 21st century.
World of Wonders contained 12 short stories and novellas published from 1944 to 1954, one short story (“Day Million” by Frederick Pohl) published in 1966, each followed by an essay explaining his views of the storytelling skills displayed by the authors. ( )

I was attracted to this anthology because Silverberg describes the work as possessing three elements in one.
" An anthology of what he regards as some of the most meaningful science fiction
" Essays on the art and craft of writing science fiction.
" Personal reminiscences by the authors

It was the second in particularly that particularly appealed to me. Aside from that, however, the forward is a largely self-indulgent (self-important) effort to define science fiction. The resulting definition is unimpressive. It is neither inclusive nor exclusive.

The introduction makes up for this dreary beginning with an interesting and informative autobiographical recounting of his development as a science fiction writer. Silverberg includes notes about writing and also personal reminiscences about notable SF writers of the 40s and 50s. In retrospect, this is the best part of the book and readers who are pressed for time might limit their reading to the introduction.

Silverberg's selection of stories seems to focus on stories that had a formative impact on him as a teen just developing his writing skills ca 1953. As promised in the forward, many of the elements of his essays are essentially a memoir. After the introduction there are few practical tips on writing short stories in general and only a few general principles on writing science fiction short stories.

Readers who are not interested in the tips on writing and the personal reminiscences will find many better science fiction anthologies.

Following is a thumbnail description of the thirteen short stories included in the anthology.

Four In One
Four explorers, absorbed by an amoeba-like creature, engage in an internal war for supremacy and survival.

Fondly Fahrenheit
A malfunctioning robot - or is it the robot's owner - begins killing people. Do the personal values and personality characteristics of people project on to their robots and vice versa?

No Woman Born
This is old fashioned SF in the sense the first 11-12 pages are a long monologue by the protagonist telling us "how it works." It then turns to an abstract discussion of the essential nature of a human. It is twice as long as the average SF story and could have been edited greatly to advantage.

Home is the Hunter
In a society in which professional killers (headhunters) vie to amass the greatest number of kills, one headhunter seeks a way to retire with honor.

The Monsters
In a society where wives are killed after 25 days and a new wife is secured from the replacement pool, the creatures debate whether humans who do not follow that practice are ethical and "human."

Common Time
Not much happens. The emphasis is on character development. What plot there is focuses on FTL travel and the adjustment of physiological time to the altered physical time. Then first contact.

Scanners Live in Vain
In order to survive the "pain" of space and pilot spaceship, individuals must sacrifice their physical bodies and become androids. But what happens to these androids when that is no longer necessary?

Hothouse.
This is part one of a five-part story that was eventually published as a book-length novel. It details the struggles of humans to survive on a planet that has been completely overrun by vegetation that is so massive it extends from earth to the moon.

The New Prime
The Prime (ruler of the galaxy) developed a series of six tests that would be used to judge the candidates for his position. The tests measure social intuition, flexibility, leadership, devotion to duty, imagination, and resolution. The Prime obtained the highest score of all the candidates but was not selected as the new Prime because of qualities he failed to test that the ruling council considered to be more important.

Colony by Philip K. Dick
Explorers evaluating a new planet to determine its suitability for colonization are attacked by microscopes, gloves, towels, rugs, and other inanimate objects.

The Little Black Bag by C. M. Kornbluth
A disgraced, alcoholic MD is the accidental recipient of a medical bag from more than 500 years in the future.

Light of Other Days by Bob Shaw
Slow glass that takes 10 years for light to pass through has an influence on an unhappy marriage.

Day Million by Frederick Pohl
Describes a "romance?" between Dora, a girl with a silky pelt, tail, and gills who is actually a man, and Don, a 187 year old tall, muscular, bronze cybernetic man who was on his way to have his legs renewed."Will you marry me?" he asked. "Wednesday," she replied. ( )

Robert Silverberg writes about how he learned to write science fiction. He includes several short stories and writes about what he likes about them. ( )

A fascinating tour with Silverberg leading the way. If you read SF, you've read most of these, but Silverberg's inroduction and notes make the book. ( )

A collection of high-quality SF stories chosen by Silverberg and glossed (in introductory and concluding comments) to illustrate principles of good SF writing. The stories are uniformly interesting, and the commentary is so good you wish there was more of it. ( )