It is revealing that near the start of Looking at Giacometti, Sylvester lists the similarities between Giacometti and another of his heroes, Wittgenstein:
There is a similar consuming dedication to an activity, and a similar refusal to take for granted accepted assumptions about the purpose and possibilities of that activity. There is a similar feeling that this activity is not a means of producing works of philosophy or works of art, but a search that can never lead to a final solution. There is a similar passion for economy [..] a similar reluctance to make their work public [...]
(it goes on)
Undoubtedly Sylvester is in one sense a man of feeling in the lineage of Pater and Berenson. He referred to 'the way I can't help writing about art, which is not unlike St Teresa of Avila's reports on her intercourse with the deity', and certainly, reading Sylvester is often like reading a review of a live event. Tom Lubbock astutely described this sort of criticism as one where 'the critic performs, not by talking to us about work to which we're both assumed to have access, but rather by experiencing the work on our behalf, for our benefit'.
An interesting thing about Sylvester's writing, however, is that this 'phenomenological' approach coexists with the side which saw the condition of modern art as a form of criticism. Sylvester found he couldn't write about the Minimalist works he loved, because the experience alone was insufficient. The quality shared by Sylvester's writing not just about Giacometti and Bacon but also Moore and Magritte, was that he was able to by turns convey a visceral experience of their work, and see it as the outcome of a comprehensible process. This says something about both the jaded post-war art world in which Sylvester developed as a critic, and his pragmatic sense of criticism as a vocation.