Bonta's poem is only four short lines, but it packs in a quiet argument. The first couplet makes a strange claim: nothing could be invented "more than an answer." In other words, an answer is the most made-up thing there is. The title, "Certitude," sets this up with irony, since the poem seems suspicious of the very certainty it names.
The second couplet turns to an image. A "little garden" is "forced to lie in beds." There's a pun here: a garden bed is where plants are arranged, but "lie" also means to tell a falsehood. So the garden becomes a picture of how certainty works, tidying something living and wild into neat rows and making it say what we want.
The speaker sounds wry and a little wary, more skeptical than angry. The mood is calm and dry, with a faint sympathy for the garden, which has to put up with being ordered. The poem leaves us wondering what we flatten when we insist on being sure.