Direct stone sculpture is not the most common method of creating stone statues. Usually, the artist makes a model, from clay or wax and often smaller than the final work. This model is then handed off to craftsmen who use specialized tools to exactly reproduce the shape of the model in stone. There is nothing intrinsically wrong with this and many fine works have been created by this method.
With direct stone, the sculptor works the stone without intermediaries. In the words of the old joke "I made a statue of a camel by starting with a piece of rock and throwing away everything that didn't look like a camel."
This has consequences. First, it is a purely subtractive process. In most other forms of sculpture, if too much is removed, it can be added back. With direct stone if too much is removed, even only a small nick, the only cure is to remove material from the rest of the form until the whole is shrunk enough that the entire surface is below the flaw. This forces the sulptor to proceed more cautiously than he would with a more forgiving medium.
Second, the process of creation becomes a negotiation between the sculptor and the stone. Each stone has a specific character,color and grain. Many contain flaws or inclusions which only become evident after the work has been started. As a result my sculptures are very different from the work I would create on the same subject if I were working in another medium.
The banana is for scale. Pictures of sculpture which give no clue whether the object is three inches or thirty feet high are obnoxious. I chose a banana as something that most people would understand. Nota Bene however, that, being, as I am, a recrudescent revenant of an age now passed, these are all English Standard rather than metric bananas.