Akademik

Одна ласточка весны не делает

One single sign of a phenomenon is not enough to prove its existance. See Одно дерево еще не сад (O)

Var.: Первая ласточка весны не делает (лета не приносит)

Cf: It takes more than a robin to make a spring (Am.). One day does not a summer make (Am.). One flower makes no garland (Am., Br.). One robin doesn't make a spring (Am.). One swallow does not make a spring (a summer) (Am., Br.). One swallow makes not a spring, nor a woodcock a winter (Br.). One swallow makes not a spring, nor one woodchuck a winter (Am.)

Русско-английский словарь пословиц и поговорок. Академик.ру. 2013.