Handwriting and a seal are connected by the inquiry into a document's attribution. The link is not simply that two unrelated objects happened to be remembered together. Both observations contribute to a shared question about provenance.
In assessing a rational connecting feature, one asks whether the clauses have an intelligible relation under a common discursive purpose. A habitual imaginative association may explain why two notions are mentally paired, but such pairing is not automatically strong evidence for a claim.
The central question is whether coordination clarifies the purpose of the discourse or merely places adjacent expressions side by side.