The Sequence of Time deals with the time-relationship  between a dependent clauses using the subjunctive and its principal clause ( i.e. the clause it is dependent on).
   The important questions are:

• What is the time level of the main clause?

• a.  Is it present or future time, i.e. is the verb in the present, future, or future perfect tense?
• b.  Is it past time    i.e. is the verb in the imperfect, perfect, or pluperfect tense?
 
• What is the time relationship between main and dependent clause?
• Is the action of the dependent clause
• simultaneous,
• prior,
• subsequent,
• to that of the main clause?

I.   Present/Future Time as the time level of the main clause
       (Tenses of main clause:  present, future, future perfect)

A.  If actions are simultaneous,  the dependen clause uses present subjunctive

video, quid facias        I see what you are doing.
videbo, quid facias      I will see, what you are doing
videro, quid facias      I will have seen, what you are doing.
 

video, quid feceris         I see what you have done.
videbo, quid feceris.      I will see, what you have done.
videro, quid feceris        I will have seen what you have done.

video, quid facturus sis         I see what you will be doing.
videbo, quid facturus sis.      I will see, what you will do.
videro, quid facturus sis.       I will have seen what you will do.

II.  Past Time as the time level of the main clause
     (Tenses of main clause:  imperfect, perfect, future perfect)

A.  If actions are simultaneous,  the dependen clause uses  imperfect subjunctive

videbam, quid faceres.        I was seeing what you were doing.
vidi, quid faceres.               I saw what you were doing.
videram, quid faceres.        I had seen what you were doing.

videbam, quid fecisses.        I was seeing what you had done.
vidi, quid fecisses.               I saw what you had done.
videram, quid fecisses.        I had seen what you had done.

videbam, quid facturus esses.        I was seeing what you would do (were about to do).
vidi, quid facturus esses.               I saw what you would do (were about to do).
videram, quid facturus esses.        I had seen what you would do (were about to do).

The basic rules above require some additional details.

If more then one dependent clause is involved

If the dependent subjunctive clause under consideration has as its principal clause another dependent subjunctive clause,  then the tense of this clause, not that of the main clause,  determines the tense of the clause under consideration.
 

main clause	first dep. clause	2nd. dep. clause
intelligisne,	ut videam (present)	quid facias (feceris)	Do you know, that I am seeing, what you are doing (have done)
intelligisne,	ut viderem (past)	quid faceres (fecisses)	Do you know, that I was seeing, what you were doing (have done) ?

 
 

 Infinitives and Participles have no effect on the tenses; determining is the tense of the next finite verb in the principal clause.
 

Cupisne scire, num ego id scio?	Do you want to know, if I know that?
cupivistine scire, num ego id scirem (scivissem)?	Did you want to know whether I knew it (had known) ?

 
 
Only  clauses dependent on an  perfect infinitive have an imperf. or pluquamperfect subjunctive.
 

scio te quaesivisse, num ego hoc scirem	I know that you asked whether I knew that.
Scio te quaesivisse, num ego hoc scivissem.	I know that you asked whether I had known that.

The Latin Present Perfect is made up of a number of verbs, whose perfect is perfect in form, but present in meaning, as
 

novi	I have learned	=  I know
consuevi	I have gotten used to	= I am accustomed to
memini		= I remember

This perfect tense is considere 'present' in time and belongs to the present/future sequence.
 

The historical present and historical infinitive belong to the past time level
 

Dependent clauses belong to this time-relationship, when their actions occur later than those of their principal clauses.

A.  Clauses of wishes and fear
 
 Already the content of these clauses makes clear, that it has to be subsequent action.
 

Present Time: pres. subj.	timeo, ne sero veniat	I am afraid that he is coming too late.
Past Time:  imperf. subj.	timui, ne sero veniret	I feared he was coming too late.

 
 

B.  Indirect Interrogative Clauses

These clauses can have prior, simultaneous, and subsequent action.
To express subsequent (i.e. future) action, these clauses use the subj. present and subj. imperfect periphrastic conjugation:  -urus sim,  -urus essem.

I.  Present Time
 
 

Action of Dependent  Clause
Simultaneous	interroga, num magister veniat	Ask, if the teacher is coming.
Prior	interroga, num magister advenerit	Ask, if the teacher as come.
Subsequent	interroga, quando magister adventurus sit	Ask, when the teacher will arive.

 

II.  Past Time
 
 

Action of Dependent  Clause
Simultaneous	interrogavit, num magister adesset	He asked, if the teacher was there.
Prior	interrogavit, num magister advenisset	He asked, if the teacher had come.
Subsequent	interrogavit, quando magister adventurus esset	He asked, when the teacher will arrive.

 

The same goes for sentences with  dubito, quin
 

non dubitavi, quin magister adventurus esset  I did not doubt, that the teacher would come.

If no periphrastic conjugation is available, the subjunctive is used.
Adverbs, as mox, brevi, statim, and others  can be added.
 

Future Time

Latin does not have a subjunctive for the Future and Future Perfect, but there are several ways to express the subjunctive idea for these tenses.

1.  If the main clause has a future tense, using pres., imperf., perfect, and pluperf. subjunctive in the dependent clause is sufficient, since the context (future in main clause) makes clear, that future time is involved.
 

Pres. & Perf. Subj. after Present Tense  (Present/Future Sequence)
Galli pollicentur se facturos, quae Caesar imperet.(substitute for fut. subj.)	The Gauls promise that they will do what Caesar will order.
Galli pollicentur se facturos, quae Caesar imperaverit. (substitute for fut.perf. subj.)	The Gauls promise that they will do what Caesar will have ordered.
Imperf.& Pluperf. Subj. after Past Tense  (Past Sequence)
Galli pollicebantur se facturos quae Caesar imperaret.	The Gauls promised that they would do what Caesar should order.
Galli pollicebantur se facturos quae Caesar imperavisset.	The Gauls promised they would do what Caesar should have ordered.

 
 

2.  Even if there is no future tense in the main clause, the context may make clear that future time is involved.
 

Timeo ne veniat.	I am afraid he will come.
Caesar expectabat quid hostes facerent.	Caesar was waiting to see what the enemy would do.

 
3.  If greater precision is required, the future active periphrastic conjugation is used.
 

non dubito quin pater venturus sit.   I do not doubt that my father will come.

 

4.  Adverbs , as mox, brevi, statim, can be used to indicate future time.
 

Non dubito quin pater mox veniat.   I do not doubt that my father will come soon.

 
 
 5.  Verbs that have no participle-stem, can paraphrase the future with futurum esse (fore)
 

spero futurum esse ut venire velit.     I hope that he will want to come.

 lit. I hope that it will be that he will be able to come. 

Table Summarizing  the Tenses in Subjunctive Clauses
 

Table of the Tenses of Subjunctive Clauses
Time Involved	Primary Clause	Dependent Clause
		simultaneous	prior	subsequent
Present/Future	present  Lat.pres.perf.  future	present subj.	perfect subj.	present subj.  -urus sim
Past	imperfect  historical perfect  plusquamperfect	imperfect subj.	plusquamperfect  subjunctive	imperfect subj.  -urus essem

 
 
 

 Sequence of Time with Infinitives and Participles

• simultaneous action (present infinitive)
• prior action             (past infinitive)
• subsequent action    (future  infinitive)

 Introductory Verb in Past Time:

simultaneous/subsequent  (present infinitive)	dixit se venire	He said that he was coming /will come.
prior  (past infinitive)	dixit se venisse	He said that he has/had come.
subsequent  (future infinitive)	dixit se venturum esse	He said that he will come

NOTE:  The Perfect infinitive may represent any past tense of the indicative of Direct Discourse:
dixit se venisse may mean:

	Direct Discourse:
He said that he was coming.	"veniebam"
He said that he came/has come.	"veni"
He said  that he had come.	"veneram"

 
 

The Seqence of Tenses with Participles
 

Participles also express relative time in relation to the principal verb.  Their action, in relation to the principal verb, can be:

• simultaneous:  present participle
• prior: perfect participle
• subsequent:  future participle.