This post is a little denser on grammar than usual, so I’ve inset helpful expositions in red.
The American comedian W.C. Fields famously quipped that if first prize was a week in Philadelphia, second prize was two weeks. I suppose that most Spanish students feel the same way about the subjunctive. If first prize is the present subjunctive, second prize is the imperfect subjunctive. Third prize, then, must be the present subjunctive plus TWO imperfect subjunctives: the ones with -ra and the ones with -se.
(If you’re rusty on the imperfect subjunctive, a decent review is here.)
For a linguist, however, the many subjunctives of Spanish are pure candy. For one thing, it’s delightfully contrarian that neither imperfect subjunctive is directly related to the original Latin version. Instead, these two tenses (or moods, more precisely) arose from two Latin pluperfect conjugations: the pluperfect subjunctive (for -se) and the pluperfect indicative (for –ra).
“Pluperfect” simply means a tense that is used to talk about actions completed before some past point in time. The Modern Spanish equivalents use compound structures, as in Si hubiera comido… “If I had eaten…” (pluperfect subjunctive) and Había comido “I had eaten” (pluperfect indicative).
The following table shows the original Latin conjugations and their outcome in Spanish.
Even more interesting is the mere fact that the two conjugations co-exist in modern Spanish. Although not as common as the -ra subjunctive, the -se subjunctive is certainly current, especially in the written language, and is understood throughout the Spanish-speaking world. This is remarkable because in grammar, a difference in form normally implies a difference in meaning. Comí, comía, and he comido are all different kinds of past tenses; voy a comer and comeré refer to imminent vs. distant future events The Spanish imperfect subjunctive is thus a striking exception. In fact, it’s the only case I’m familiar with in any language where two parallel constructions co-exist in the core of the grammar. (If you know of any others, please share them!)
Essentially, what we are seeing here is a snapshot of a slowly moving change in the language. The -se subjunctive came first; Ralph Penny dates it to Old Spanish, roughly 1000 to 1400 CE. Its evolution was relatively simple, involving only a shift in time (from pluperfect to normal past tense) along with shortened verb endings as a result of normal sound change. The -ra subjunctive took longer to evolve because it also involved a switch from indicative to subjunctive: that is, from actuality to possibility. Penny dates its emergence to the Golden Age (1500 to 1700), and its overtaking the -se subjunctive to “more recent times”.
In the Spanish imperfect subjunctive, then, the language’s past and future co-exist peacefully in the present. Although this is an unusual situation in grammar, it’s one that we’re used to in vocabulary, which changes much faster. A contemporary American English speaker, for example, understands the outdated swell and nifty, the timeless cool, and possibly the trendy swag and dope. The Spanish parallels would depend on dialect, but just consider the exuberant redundancy of maravilloso, fantástico, estupendo, fabuloso, excelente, fenomenal, tremendo, and buenísimo. The co-existence of the two Spanish subjunctives is therefore simultaneously exotic and familiar.